Gerbview Shows Only Blank Window

I have created Gerber files and drill files. They all show up on my project listing. I open Gerbview and from the file menu I select Open Gerber Plot files and they all show up in the list in the file-open window. I select F_Cu, B_Cu, F_Silk, B_Silk, F_Mask, B_Mask, and Edge_Cuts and then I click on “Open” but the Gerbview window remains blank. The cmp and Net pulldown menus are all populated with entries but the main Gerbview window remains blank. I must be doing something wrong but I do not know what it is.

What is the filesize of your Gerbers? Could they be empty?
You can also look at them in another (online?) gerber viewer to narrow down where the problem might be.

Checking the gbr file size was the first thing I did. They all have content (e.g., F_Cu.gbr is 43KB, B_Cu.gbr is 561KB).

I uploaded the F_Cu file to https://www.pcbgogo.com/GerberViewer.html and it displayed fine.

Please post a screenshot.

If you’re on 5.1.x and macOS, select Preferences -> Modern Toolset (Accelerated)

Well, OK, that fixes the problem.

While we are at it, how if at all do I specify what I want my hole size to be? I did not see anywhere to enter that information.

Not quite sure your question… Hole sizes are defined within your PCB… But if you want to review the hole sizes in GerbView, you also need to load the drill file:
2021-04-08 10_46_56-GerbView
Remember to make sure the blue triangle selected layer indicator in the layer list is on an empty layer (AFAIR that blue triangle will automatically move to the next empty layer when you load your gerbers).
2021-04-08 10_47_12-GerbView
Here Graphic layer 3 is selected. I haven’t loaded any gerbers in my example so all the layer names are still at their defaults. Disclaimer: These screenshots are of the current stable (v5.1.9), other versions may look a little different.

Thanks for the informative reply. I am now realizing that by the time I get to the Gerber file stage of my design it is way too late to define hole sizes for individual components; that is simply the place where I first noticed this aspect of my design. I just posted a thread asking where at the component level I can find the hole size data for specific components so I can edit hole sizes for individual components. I think that is the more appropriate inquiry.

I consider my initial problem and question to have been solved. The users here are absolutely great in helping out novices like me!!

If you used standard lib footprints, all of the hole sizes should be ok. It is not necessary to set hole sizes as a separate task.

If you have used custom footprints, the holes should be defined within the footprint.