I found this behaviour slightly surprising, but on reflection it makes sense. Pd doesn't seem to check deeply into subpatches when looking for DSP feedback loops.
I started making a simple waveguide synth and decided, for a change, to work on the feedback mechanism inside another subpatch. I kept getting DSP loop error even though the signal path contains a [s~] and unique matching [r~]. Making the feedback loop require a [send~] and [receive~] in the outermost block seems to defeat the use of smaller blocksizes in subpatches.
Anyone care to comment on this (attached example). Or am I understanding this incorrectly?
Cheers. Andy