I've tried to find something on this topic in existing discussions, but I couldn't - forgive me if I'm being redundant.
I'm using Pure Data on Bela Mini exclusively. I've observed unintuitive behaviour when it comes to setting a proper block size for some of my projects - I do it the usual way (or at least what I think is the usual way) - when I'm getting the "Underrun detected: 1 blocks dropped" message, I set a higher block size in IDE settings, usually settling on something that works. Nevertheless, after making sure the project is set as "run on boot" and restarting Bela, I tend to get audible audio dropouts, red light blinking etc. After refreshing the IDE, I get a string of "Underrun detected..." messages, but after clicking the "stop" and "build & run" buttons in IDE, the project restarts and it's running just fine. Situation repeats when I try to run Bela in standalone mode again (i.e. not starting the project from within the IDE, doesn't matter if I power it from pc or other power source) - the problem starts anew.
I've had this issue with different PD patches and with different Bela Mini boards (I'm currently using three or four for different projects and they all seem to have this issue). Any thoughts?