Problems with layers not showing in after effects 2020

I hope you got this solved.  I was having the same problem.  I ended up swapping out the layer item (for an identicle one) and it showed again. 

The first step in troubleshooting a comp is to turn on both the switches and modes column in the timeline by clicking the first two icons at the bottom left corner of the timeline, select all layers and press the 'u' key twice. This will reveal all modified properties in all layers you have selected. Look for keyframes or modified properties and effects. If any of the layers have effects applied as indicated in the FX column of the Switches column turn off those effects one by one. If you still can't find the problem start soloing layers one at a time or turning off layers starting at layer 1 until you find the layer that is causing the problem. 

When you post screenshots, try and have switches and modes columns visible and the modified properties of the layers showing so we can see what is going on. Trying to diagnose without that information means we can only make a wild guess. Martin made a good guess, but it is only a guess.

Check if the layers have opacity of 0 or scale of 0. If they are parented, check if the parent has a scale of 0.

*Martin