I tried to import the flow into other powerapps. The parameters fall off in those apps as well. So, its not a specific app problem. However, now I'm afraid to touch any of my flows. I cannot afford a problem that I cant fix!!! This would completely take us down. We rely on this for our production operations. HELP!!!
I added some "Initialize variable" actions at the top of the flow, then ask the parameters in these actions instead of asking it directly on the actual field that needed it. On the actual field, we can just use the variable.
It's working fine on my case, hope it's useful if you need quick workaround.