If your training without tags there should be a notification I was having issues training with
--caption_extension "txt"

only to realize that I needed a "." in the extension so
--caption_extension ".txt"

The training still went through ignoring tags without any notification that it couldn't find any tag files this took me days to sort out as loras can take a while to train and i was trying to figure out why all my loras suddenly sucked I know that tagless training was added in an update but a warning would go a long way in preventing errors especially if the person explicitly passed --caption_extension