Whenever digging up a dirt mound, the text pops up "can't use actions". Can't use...what actions? It doesn't prevent digging up the treasure chest or looting it, it is just an annoying text to see each time.
I had that on one of the early mounds. It also said I didn't have shovel even though two of the party were carrying one. I did some moving the shovels around and suddenly we were back to digging like a good 'un. Not had it since that one incident.
I see the text every single time I dig up one of those mounds, without exception. I do remember however the first time I detected one, I didn't yet have a shovel, so I am wonrdering if that then causes it to get buggy...