@ toddschreiner
Did you happen to password protect/encrypt your data file when using the Mac for 2018 return, either with the Mac keychain access or without?
If you did, see this FAQ on how to remove it in either of those cases using your Mac and 2018 program.
https://ttlc.intuit.com/community/tax-data-file/help/how-do-i-access-my-password-protected-turbotax-...
