WTF!My outdoor2 lower branches wilting and falling off?

I've checked for bugs and nothing Using pro mix hp I even put some Diatomaceous Insect Dust on top .water every 3 days I check the bottom of the pot for standing water and nothing Checked ph 6.0 -6.5 checked runoff and its good. temps been 20-30 Celsius day. It hasn't been very windy either. not sure what's going on Just wondering if anyone has a clue ?

Chipmunk/ mouse eating, building a home in the root ball? That looks like what they did to my tomatoes .

I had that happen to an outdoor plant last year, chalked it up a root issue. Rest of the plant looked and finished great.

Thanks for the advice guys