Android Talk crash after select attachment

Hello,
i use the actual Nextcloud Hub Version at an own server (Intel Nuc) with Ubuntu. I also installed the Talk app at Web Interface and at two different Smartphones (Android) from tow users (actual versions). At both Smartphones (Sony and Samsung) it show the same problems: After I select the + Button to insert a attachment it will show me the shared directorys for the user. After I select one of the shared directories to navigate through this directory to subdirectories, the Talk app crashes and close. A message will be displayed, so it is only possible to send a feedback message or restart. So I dont know, could it be a problem of my installation or is this a (known) bug of the Android App? At the Webinterface (Browser) I can navigate the diretories and select a file. Would it be helpful to send the Feedback with report?
At the message there are many things that will transferd, Smartphone, Android Version, running Apps, System log, Event log and: Crash, Name the exceptional class = java.lang.NullPointerException, Source file: ReadFilesystemOperation.java, Source class: com.nextcloud.talk.components.filebrowser.webdav.ReadFilesystemOperation; Swelling method: readRemotePath; Line number: 90 …
Maybe this will help… I dont know how to save this log…

Thanks for the help…
Maggi

Edit: Maybe it could be a problem with the shared directories. The visible directories are shared to a group, this directories are visible to select this at talk, if I start a conversation with a member of this grouup seperate. If I click to this shared direcories to see what subdirectories or files are in this the app crash. Only the diretories are visible which are shared for the group, at the webinterface, the subdirecories are automatic shared also with all files are in.
So I share a file to the user I want to chat, without a directory at th top level and than I can select this document to attach it with talk. After I delete option to share to the User, the document is not visible anymore at the chat history at the talk app, only a note that the shared document isnot there anymore.