Excuse me in advance if this problem only pertains to me and not others.
Some background first. I used Slimjet to play and have it go directly to the game client, and have no problems with flash that way.
My default browser is Firefox. I had not updated Firefox nor flash. I could get onto wgt.com and the flash area worked just fine, then a few days ago I either had to do 1 of 2 things. Either I had to reactivate flash on every page or leave it alone to go to the forums.(I don't use Firefox to play)My left side is now all grey
I think what you are experiencing is how websites are starting to treat flash. Chrome did this awhile back, now it appears that wgt is blocking flash to some extent(or making it harder to use)
Wgt is developing the new PC version, patterned after the Mobile version, It may be a way to force us to it.
They keep saying something about until the end of 2020 to get the new version correct. I have seen many game sites that are doing different things concerning flash.
I know of 1 site that isn't planning to still have flash games on it past March 2020