@Philipp @Kevin_Murray
I have rewritten the entire syncing algorithm.
It now uses the new versioning API from Dynalist and should be faster and more reliable.
I have also upgraded the database I am using which may resolve some issues.
The inbox is also more consistent now by either using your tagged #primary #inbox or automatically detecting your configured inbox and setting the tags for you. I completely avoid using the inbox API call now because it resulted in not being able to show added items consistently.
Please try out the new version in the beta channel https://play.google.com/apps/testing/com.louiskirsch.quickdynalist
Let me know whether your issues are resolved.
Thanks for your help!