If you are using a Mac with one screen, you may not have enough screen real estate to see your PowerPoint along with the other Zoom windows. Here are directions on sharing an adjustable PowerPoint window in Slide Show mode
Step 1
You can change the way a slideshow displays by going to Slide Show > Set Up Show:
Step 2
On the popup, under the "Show type", choose the Browsed by an individual (window) option
Step 3
The slide show will open in an adjustable window. You can then open the chat and attendee pods around it