Yeah late to the game - but got the issue anyway today 
Another workaround that may help is to:
- look for the original name of the Golden Image VDI (the one that is missing)
- rename the new updated Golden Image VDI to that OLD name
- edit the pool, and you have your OK button back
If you dont like the old name, because it may have an old date in it, just side step by doing the above, then:
- switch the Golden Image VDI to some other valid existing Image, and save pool settings
- Then rename the new updated Golden Image to proper name
- then edit Pool and swap back to wanted Golden image.
Yes it is a bit convulted, but the only option if you dont have Flash and you dont want to remake your pool from scratch...
OK for some reason this works only on some pools - had to dig up an old flash MSI installer, and put Edge in IE mode, then i could fire up the FlexAdmin interface and fix the issue