Hi @john.shelley,
As @yukihyou stated above, Quicken (Intuit software in general, actually) has a bit of a reputation for not working properly in sync scenarios. I had previously investigated an issue with Quickbooks, which is made by the same company as Quicken. What I found was that it seemed that Intuit was actively trying to prevent this type of scenario. You can take a look at this post for more details: Odrive is not syncing my files on my laptop (Quickbooks qwb)
For Avast, I do not know. odrive doesn’t do any manipulation of data and syncs it as it exists on the system. Is it possible that the file is open by the Avast process on the current system and it is modified in some way when that happens. I suppose calculating a hash of the the files and comparing on the 1st and 2nd system would show us if there are any actual differences in the files. Have you tried zipping up the file first, before syncing?