Yes it is happening intermittently but as soon as it starts to happen the user has to close the meeting and start another one to make the chat working properly again.
Unfortunately I am not yet able to replicate this issue in a debug environment so collecting the log can be a little bit challenging, especially because, in the release build of the app, the log is obviously disabled.
Can you clarify in which cases the SDK can return the SDKERR_NO_PERMISSION?