I get no output from the following code even though I know a1 is
receiving a signal. If I comment out the comb filter line I get the
audio I would expect. Seems odd that my a1 variable is zeroed because
of a reverb time of 0, albeit rather silly to have such a reverb time.

a1 inch 1
aLeft comb a1, 0, 0
outs a1, a1
endin

Csound 5.19.02 linux....