Storage appears to be connected, but no files (owncloud or dropbox) are shown

[unalignedcoder]

Centos 7, Apache 2.4, PHP 7.4, Owncloud v10.9.1

Trying to set this up for user admin only

I get different results with Firefox or Chrome, both fails.

The storage connection to dropbox seems fine (green light).
The scoped app in Dropbox is created following instructions. In addition, I have given it all permissions.

When I switch to Files (in Firefox), it shows no files.
Only the breadcrumb at the top (Home > Files).
If I go into settings, it shows I use 0 B!
If I click on "external storage", it shows the dropbox mount but again, clicking on it shows no files.

When I switch to Files (in Chrome), it shows only 4 folders out of 9.
(Not the first 4 in alphabetical order. It skips one.)
The dropbox mount is not among them.
As above, if I click on "external storage", it shows the dropbox mount but no files.

The Owncloud log shows this:
"user":"admin","app":"PHP","method":"PROPFIND","url":"/remote.php/dav/files/admin/","message":"Cannot modify header information - headers already sent by (output started at /home/username/public_html/owncloud/lib/composer/sabre/xml/lib/Serializer/functions.php:198) at /home/username/public_html/owncloud/lib/composer/sabre/http/lib/Sapi.php#70"}

and this:
{\"Exception\":\"PDOException\",\"Message\":\"SQLSTATE[42S22]: Column not found: 1054 Unknown column 'fileid' in 'where clause'\",\"Code\":\"42S22\",\"Trace\":\"#0 \home\username\public_html\owncloud\lib\composer\doctrine\dbal\lib\Doctrine\DBAL\Driver\PDOStatement.php(117): PDOStatement->execute(NULL)\\n#1 \home\username\public_html\owncloud\lib\composer\doctrine\dbal\lib\Doctrine\DBAL\Connection.php(1303): Doctrine\DBAL\Driver\PDOStatement->execute()\\n#2 \home\username\public_html\owncloud\lib\private\DB\Connection.php(191): Doctrine\DBAL\Connection->executeQuery('SELECT * FROM `...', Array, Array, NULL)\\n#3 \home\username\public_html\owncloud\apps\dav\lib\DAV\AbstractCustomPropertiesBackend.php(242): OC\DB\Connection->executeQuery('SELECT * FROM `...', Array, Array)\\n#4 \home\username\public_html\owncloud\apps\dav\lib\DAV\FileCustomPropertiesBackend.php(158): OCA\DAV\DAV\AbstractCustomPropertiesBackend->fetchProperties('SELECT * FROM `...', Array, Array)\\n#5 \home\username\public_html\owncloud\apps\dav\lib\DAV\AbstractCustomPropertiesBackend.php(209): OCA\DAV\DAV\FileCustomPropertiesBackend->getProperties('files\admin\my-...', Object(OCA\DAV\Connector\Sabre\Directory), Array)\\n#6 \home\username\public_html\owncloud\lib\composer\sabre\dav\lib\DAV\PropertyStorage\Plugin.php(84): OCA\DAV\DAV\AbstractCustomPropertiesBackend->propFind('files\admin\my-...', Object(Sabre\DAV\PropFind))\\n#7 \home\username\public_html\owncloud\lib\composer\sabre\event\lib\WildcardEmitterTrait.php(89): Sabre\DAV\PropertyStorage\Plugin->propFind(Object(Sabre\DAV\PropFind), Object(OCA\DAV\Connector\Sabre\Directory))\\n#8 \home\username\public_html\owncloud\lib\composer\sabre\dav\lib\DAV\Server.php(1052): Sabre\DAV\Server->emit('propFind', Array)\\n#9 \home\username\public_html\owncloud\lib\composer\sabre\dav\lib\DAV\Server.php(984): Sabre\DAV\Server->getPropertiesByNode(Object(Sabre\DAV\PropFind), Object(OCA\DAV\Connector\Sabre\Directory))\\n#10 \home\username\public_html\owncloud\lib\composer\sabre\dav\lib\DAV\Server.php(1662): Sabre\DAV\Server->getPropertiesIteratorForPath('files\admin', Array, 1)\\n#11 \home\username\public_html\owncloud\lib\composer\sabre\dav\lib\DAV\Server.php(1642): Sabre\DAV\Server->writeMultiStatus(Object(Sabre\Xml\Writer), Object(Generator), false)\\n#12 \home\username\public_html\owncloud\lib\composer\sabre\http\lib\Sapi.php(83): Sabre\DAV\Server->Sabre\DAV\{closure}(*** sensitive parameters replaced ***)\\n#13 \home\username\public_html\owncloud\lib\composer\sabre\dav\lib\DAV\Server.php(490): Sabre\HTTP\Sapi::sendResponse(Object(Sabre\HTTP\Response))\\n#14 \home\username\public_html\owncloud\lib\composer\sabre\dav\lib\DAV\Server.php(253): Sabre\DAV\Server->invokeMethod(Object(Sabre\HTTP\Request), Object(Sabre\HTTP\Response))\\n#15 \home\username\public_html\owncloud\apps\dav\lib\Server.php(345): Sabre\DAV\Server->start()\\n#16 \home\username\public_html\owncloud\apps\dav\appinfo\v2\remote.php(31): OCA\DAV\Server->exec()\\n#17 \home\username\public_html\owncloud\remote.php(165): require_once('\home\username\...')\\n#18 {main}\",\"File\":\"\home\username\public_html\owncloud\lib\composer\doctrine\dbal\lib\Doctrine\DBAL\Driver\PDOStatement.php\",\"Line\":117}"}

In the Firefox developer tools I get this:
XML Parsing Error: not well-formed Location: https://owncloud-server/remote.php/dav/files/admin/ Line Number 2, Column 3983:
and
Uncaught (in promise) TypeError: can't access property "permissions", this.dirInfo is undefined

In Chrome, nothing of relevance.

To be noted that, as soon as I disable external storages, or delete the dropbox mount, everything goes back to normal.

[unalignedcoder]

The above problem seems to have been the result of migrating certain tables from a nextcloud installation.

In particular, oc_properties had a wrong schema as a result of migration, and the column fileid could not be found.

Restoring the original schema seem to get this app to partially work, and other webdav functionalities that were broken as well.

Now I can see all the files as well as the dropbox mount among them.

However, the dropbox mount appears to be empty, so not fully resolved.