Safe mode works fine
What monitor make/model do you have?
A few more things for you to try:
1) Unplug & replug the Display Port cable (both ends) to to ensure solid connection. Could be a loose connection, and sometimes Display Port can be more temperamental depending on the monitor.
2) After windows boots (and you loose signal), unplug power to the monitor and then plug it back in. See if that helps Windows detect the monitor again. Make sure the power cable is snug. Also, unplug long enough that the power light goes off.
3) If the above two don't work: Since bios mode and safe mode seem to work just fine, it could be a driver problem (although I don't think it is). Have you tried installing a much older version of the driver (like from Oct 2018 timeframe)?
Unplugging the DisplayPort cable seems to have worked! My computer is running again as normal. Thanks for all your help. Do you think that buying a new cable could result in a more secure connection?
Glad it worked out! Small victories.
I'd say watch to see if the connection works its way loose again ... and if it becomes an issue, then consider buying a new DisplayPort cable that may have a "more secure" latching mechanism (I'm not sure if yours has a friction lock or the push-button type of locking mechanism).