can share application but not a screen

I just did a zoom meeting and was given co host privileges so I could make sure I had everything working.  I could share a screen or application.  It worked well.  I did another with the same person as host and all I could see that I could share was the application. It never gave me a choice to choose a screen to share. Did a setting change?  the second meeting I had trouble on had a number of attendees, would that affect it?  Kinda confused and got another meeting with same person in a couple days.