IOS client 2.7.2 - can't upload to Server 6.2.7 "waiting to upload"


I’ve got serious issues with the IOS client 2.7.2. I can’t upload anything from my iPad with the client. I create a folder, tap “upload”, select some pictures from the iPad album and all it does is to show the message “waiting for upload” on each added file. But the upload never starts.

Doing the same upload via the browser works without any issues, that’s my current workaround. Any ideas what might be the problem here?