What settings are you using in the Edit>Fill dialog?
What version of photoshop and operating system are you using?
Sorry about the lack of details. Here you go:
Adobe Photoshop CC
on Mac OS X 10.12.5
Fill Settings (as shown in Actions tab):
I had also tried the Fill action by preceding it with setting a foreground color, then Fill with the foreground color, but it still popped up the dialog.
Yes, positive. It acts as if that box is checked. I've tried toggling it on and off, but the dialog still comes up.
Can you post a screenshot of one of the actions showing all the steps?
Anything unusual about the documents your running actions on?
What color mode and bit depth are the documents?
Before each Fill step in your action there is Apply Locking Current Layer.
What kind of locking of the layer is that?
If you disable that step does the Fill dialog still appear when running the action?