I am a fellow user. I've given you one way to work around this. That is making shading of fields active for the selected field.

I have no idea why you are seeing what you are seeing. Microsoft keeps messing with us trying to "improve" things. In addition, other programs, called Add-Ins, make changes on a regular and unannounced basis to Word. Inless you are very unusual, you have Add-Ins, even if you did not intentionally install any.

You and your wife would be ahead, regardless of resolving this issue, using Content Controls.

If neither the work-around nor using Content Controls work for you, try starting Word in safe mode and see if the problem is the same. That is a diagnostic step to work on troubleshooting.
Open Office apps in safe mode on a Windows PC - Microsoft Office