I don’t know if the problem is just that, but in my opinion there are some bad welds
have you make a continuity test with multimeter to see if there are no welds that are in contact (and that should not be)
why don’t you use a stripboard rather than a plate with only studs ? it would simplify your life for your soldering.
without really wanting to be unpleasant, you would have to take care of your welds, look here at the result with beautiful welds on the same type of plate
good welds are very important and your problem may come from poor contact between components
(I hope you understand that this review is friendly)