Try this method:
1. Edit the flow, deleting the parameter... save...
2. Re-add the "Ask in Powerapps" parameter, save.
3. Go back to your PowerApp, then do the remove/readd the Flow.
I had same issue, but resolved.
In my case, some parameter named "required" and "properties" is lacked from "triggers" section of definition.json file.
(You can find this file in downloaded package archive.)
Please fix this file, then repackage and upload.
I'm sorry for my poor english.
In above case, Flow get 5 arguments flom Powerapps.
If bug is occured, some (or all) parameter (foo1～foo5) is lacked.
Seems to be intermitant, was able to work arround the issue this morning by deleting and re-creating the variables in flow. However I just tried to do another a few hours ago and the issue appears to be back. Did have a ticket open with PowerApps support but first line closed it as when they looked creating new variables worked arround the issue.
I had a similar issue yesterday. I had to delete an action and recreate it. Perhaps re-creating the variables would have worked. Not sure. But yes, seems there is a lingering issue.
I am having similar issue. I tried creating a new flow from scratch - and only 3 steps. Trigger=PowerApps; Intitalize variable1 to "Ask Powerapps", Initialize variable2 to "Ask Powerapps". Save my Flow, then reopen it in edit, variables inital value is blank....
What type of variable is it? string? integer??
If it wont work that way, follow with a Set Variable action, and put the Ask In Powerapps in there instead... see if that will fly. Sometimes the variable type matters... But shouldnt for a string or integer. If this is an array... that is a whole different beast. I can refer you to a different post for that if that is what you are trying to do.
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