try clearing the Windows icon cache:

Thanks for the help again, Bill.

I tried the instructions on the link you posted, and I also found some older versions of WSJT-X still lurking in a Windows backwater...

However, the cache clear did not work completely on my copy of Windows 10 Pro so, armed with the advice about needing to clear the Icons cache, I did a search and came up with this link

https://windowsloop.com/clear-icon-cache-windows/

It needed me to run a CMD: window, but I've done that before so wasn't frightened by the "DOS" prompts.  After clearing the cache again I reinstalled a new copy of 2.4.0-rc3 and the wsjtx icon was back again.  Working through re-setting the shortcuts, along with setting up the two radios and audio settings, I'm nearly back to being fully set up for both of my radios using 2.3.0 and 2.4.0-rc3 again.

Cheers - Dave (G0DJA)