Hey @Oliver_Sturm,
Thank you very much for keeping in touch — whenever it works for you, we’re glad to hear back.
If a reinstall does not help, it is very likely that you might be affected by an issue we’re aware of. I am so sorry… 
This is something we’re continuously investigating and working on. With help for our subscribers, we’re able to identify causes and fix them. Would you please keep an eye on our posts here on this issue?