Which version of Quicken are you running? (Help > About Quicken)
If you are not running R49.33 you might want to consider updating to it because one of the things it does address is some paychecks being improperly altered. You can view the Release Notes and download the Windows Manual Patch Update (used to be called the Mondo Patch) from https://www.quicken.com/support/update-and-patch-20182019-release-quicken-windows-subscription-product .
If you are already running R49.33: Do you have backup files you can restore that might not have this issue present?
BTW: When a transfer says an account no longer exists it usually means that account has been deleted from Quicken. If that is the case, the transfer cannot be fixed because deleted accounts cannot be restored….except from a restored backup file that was created before the account deletion occurred.
You should not need to go back further with your backup files than to the one made just before the problem started appearing.
Sometimes a version update will not install properly which can cause some odd and unpredictable behavior. Just my opinion but it seems to me that this happens most frequently when updating the version from within Quicken instead of downloading the patch from https://www.quicken.com/support/update-and-patch-20182019-release-quicken-windows-subscription-product .
If the issues you are seeing was caused by a bad version update process, then you might want to consider uninstalling Quicken and then download a fresh copy of Quicken and install that. You can download and install the fresh copy of Quicken from your Quicken.com online account or from https://www.quicken.com/support/how-do-i-download-quicken-quickencom-after-i-buy-it .
You can download previous Mondo Patches (now called Manual Patch Updates) at https://www.quicken.com/support/reinstalling-and-patching-your-quicken-subscription-version-after-your-membership-has . Click on the Mar 2023 link to see the download link for R48.15.
BTW, if your Roth 401(k) is held in the same account as a non-Roth 401(k), then the new Roth feature has some significant issues and it is not ready for prime time. So R49.XX would disappoint you regarding this.
If, however, your Roth 401(k) is held in a standalone Roth IRA (yes, Roth IRA) account with no non-Roth 401(k), then it does seem to work quite well (with 1-2 simple workarounds required).
If you want to read more: Re: New Roth 401K feature not working correctly.
I have to change the paycheck every time I open Quicken. It keeps switching it to monthly rather than twice a month. I deleted the paycheck and re-entered, but it still does the same thing. My next step is to just set up two paychecks, each monthly. [Removed - Off Topic/3rd-Party Software]
(Deleted comment since it was redundant.)