I cleared out Flash Player in mid July, see "Flash 'in the pan'?" thread below (under W8.1) and installed it anew ...
https://get.adobe dot com/flashplayer/ [replace space"dot"space with just a "."]
... on 16th July - no problems (yet).
Now:-
Windows 1O
Firef0x 39.O
Adobe Flash Player 18.0.0.209 n.b. Firef0x "Add-ons Manager" calls it "Sh0ckwave F1ash 18.0.0.209" and in smaller print "Sh0ckwave F1ash 18.0.r0"
0,0'n'1,1