NC 13.0.1, encryption, shared folder, bad signature

I’m suddenly having issues with an encrypted instance.
The files once uploaded into folders, whereas they’re shared via groups and users, are suddenly not accesible anymore.

And yes, I know, unless its REEEEEALLY necessary, local encryption shouldn’t be used at all - but some people trust it a bit too much and activate anyways.

OS: ubuntu server 16.04.4x64
NC 13.0.1 (updated from 10->11->12)
PHP 7.0.28
Apache 2.4.18
MySQL 5.7.21

0. /var/www/html/nextcloud/apps/encryption/lib/Crypto/Crypt.php - line 465: OCA\Encryption\Crypto\Crypt->checkSignature('skMZ9INo6/GGnYi...', 'VClru\xF8v\x14">\f\x93u\xC3\xF9...', '80f09447af61cf9...')
1. /var/www/html/nextcloud/apps/encryption/lib/Crypto/Encryption.php - line 380: OCA\Encryption\Crypto\Crypt->symmetricDecryptFileContent('skMZ9INo6/GGnYi...', 'VClru\xF8v\x14">\f\x93u\xC3\xF9...', 'AES-256-CTR', 1, '0end')
2. /var/www/html/nextcloud/lib/private/Files/Stream/Encryption.php - line 464: OCA\Encryption\Crypto\Encryption->decrypt(*** sensitive parameters replaced ***)
3. /var/www/html/nextcloud/lib/private/Files/Stream/Encryption.php - line 295: OC\Files\Stream\Encryption->readCache()
4. [internal function] OC\Files\Stream\Encryption->stream_read(3537)
5. /var/www/html/nextcloud/3rdparty/icewind/streams/src/Wrapper.php - line 83: fread(Resource id #36, 8192)
6. /var/www/html/nextcloud/3rdparty/icewind/streams/src/CallbackWrapper.php - line 91: Icewind\Streams\Wrapper->stream_read(8192)
7. [internal function] Icewind\Streams\CallbackWrapper->stream_read(8192)
8. /var/www/html/nextcloud/3rdparty/sabre/http/lib/Sapi.php - line 80: stream_copy_to_stream(Resource id #39, Resource id #41, '3537')
9. /var/www/html/nextcloud/3rdparty/sabre/dav/lib/DAV/Server.php - line 498: Sabre\HTTP\Sapi sendResponse(Object(Sabre\HTTP\Response))
10. /var/www/html/nextcloud/3rdparty/sabre/dav/lib/DAV/Server.php - line 254: Sabre\DAV\Server->invokeMethod(Object(Sabre\HTTP\Request), Object(Sabre\HTTP\Response))
11. /var/www/html/nextcloud/apps/dav/appinfo/v1/webdav.php - line 80: Sabre\DAV\Server->exec()
12. /var/www/html/nextcloud/remote.php - line 164: require_once('/var/www/html/n...')
13. {main}

any ideas?

This might be related to our problem where files break on server-side encrypted instances when they are moved between different shared folders. As it seems Nextcloud breaks the entries in the oc_filecache table when doing so.