Just went through the routine update from 51.12 to 52.20. Opened my Quicken file and watched the online sync occur which zeroed out my Wells Fargo mortgage account. I have the mobile and web sync turned off. But the update DISREGARDED that switch and messed up my account. Unfortunately, I did have my Wells Fargo account linked at one point in time, but no longer downloading. I removed the online services from that mortgage account so this won't happen again, but it should not have been a problem if the do-not-sync setting was verified and honored by the update.
I had to reinstall 51.12, turn off internet access on my laptop, run Quicken, and remove Wells Fargo online services. Enabled internet access and ran my weekly transaction downloads and all seems better again. Checked the support community and looks like lots of other issues with 52.xx, so I'll be holding off any more updates until the bugs get squashed.