Shift and other key commands not working in InDesign

We are experiencing keyboard command issues for users in InDesign CC2019 (InDesign only, keyboard shortcuts work in other programs and other Adobe products, like Illustrator). Users cannot use the following very common keyboard commands:

• shift + return = line break
• shift + click/drag = proportionally resize items
• alt + click/drag = copy object

Users with issues have the following running on their machines: High Sierra and Sierra.

I am running Catalina and do not have these issues, except for the shift + return. I am able to click and drag to resize proportionally or copy, but we have quite a few reports of this and it does hamper productivity quite a bit. Are there any solutions available?

One other odd thing: We have one user who was able to get shift + return to work, but only on new documents, not existing documents. 

I've seen posts about this on here, but they are a few years old. Starting a new thread in case this continues to be an issue for others.