This is what I got after e few days. Not what I hoped for as this could become a case of being stuck between on one side C3 and on other side Dropbox, each being sure it is not them. I hope someone from Construct can help to at least make the claim it is on Dropbox side via the *developer link* below. Any help appreciated because using it is dead right now and I think can't use a dropbox-folder in another way without using 'export' all the time. I copy paste their last answer here:
Hi,
Dropbox has an open API - which means that anyone can create custom solutions that integrate with Dropbox accounts. The problem you’re experiencing appears to be caused by another app or service you’re using, not by Dropbox. We’re unable to provide support for third-party apps or services.
The best way for you to get assistance with the problem is to reach out to the company that makes the app or service for support. They'll be a better resource for you to review this in more depth.
If ultimately the developer of this integration suspects this may be an issue on Dropbox's end, please request that they reach out to our developer support here:
dropbox.com/developer
This way, our team can better understand the specifics of the third-party app, analyze the requests made to Dropbox, and review the feedback the third-party app is receiving.
If the developer determines the error comes from something on our end, they can raise a ticket with our API team dropbox.com/developers/contact
Please let me know if you have any other questions.
Best,
Billie
Enhanced Support | Dropbox