I have seen this too previously and now - Gil - it is not specific to the 4.1.13 issue
(and thanks to you / Dan for the change from 4.1.13 - normal lightning service has resumed)
The effect on the grid loses the focus (If that is the right terminology), so then it wont matter what you do , it just reverts back to what it was before the change.
I have found that if I click on a blank area of the grid and then click on the effect back again - sometimes more than once , you can "see" when the focus returns to it - cause it kind of changes colour ie brightens and then you can changes the settings or colours.
Occasionally , I will have to shut down xLights and start it up again ...