tree bags not draining

i have tree bags in a few places and have had good luck with them last year and mostly this year. a few weeks ago a bag i have on a fig tree mostly stopped draining. It took about 3 weeks including shaking and still wasn’t empty. now one on a plum tree was filled a week ago and is still mostly full. both trees are small and in their first few years. in dry season so there has been less than an inch of rain in the last 5 weeks.

any idea why they aren’t draining or what i can do?