I agree, something is broken. I'm running R48.9 (not the latest release) and it trashed my data file removing ALL of the accounts and replacing them with accounts named account_# and it also created a data file with the _0 appended to the file's name which Quicken could not even open.
I will flag your post for the moderator to report back to the developers.
[added] A copy of the original data file was not put in the Validate folder for safety which it has always done in the past. I had to go with a backup I made just prior to testing this to get back to normal.