RE: Problems opening Dynamic Worksheet produced from Dynamics 365 Online
My name is Tyson Bosse and I work with our Dynamics 365 Office Integration support team.
This is the article you will need to go through:
Troubleshoot export to Excel - Power Apps | Microsoft Docs
The main issue here will be this url in step 3:

We will want it to look like above with the "tweener" information. Sometimes, this will be showing a url for the error message you would get in step 5 below:

The url gets corrupted if you hit "ok" on this page and then hit "import". The url then is replaced with this error message url instead. There is no way to change or fix this, so you would need to re-export the file to Excel, then when you are prompted for credentials and hit the above error page (this is a good thing). You instead will just close out this error window and then you should be able to refresh the data.
Please run through this to see if it fixes your issue.
Thanks,
Tyson