[Designer file missing large number of layers]

I'm hoping someone may be able to help. I have Designer for Windows and iPad. I have been working on a file with a fairly large number of layers, not more than two hundred, in the Windows version 1.6.5.123. I saved the file to OneDrive. I opened the file on Designer for iPad version 1.6.2.42. it took a very long time to open and showed what looked like part of the file, but not the entire file. So I closed the file. I went back to the computer and opened the file there. It is now missing many layers. The file size on the disk appears to be the same, but I cannot see any of the missing content. I went into OneDrive and reviewed previous versions, but none of them were recent enough to have any of the content.

 

Is there any hope I can get those layers back? Is this a regular issue when moving from desktop to iPad if the file is large or complex?

 

I did search the forums but did not find any discussions of this. I apologize if this has already been covered.