I have an itinerary that works fine in oldmatrix but generates an error in newmatrix:

lax-cur
aa dfw aa mia aa
f ~bc=b
aa mia aa dfw aa
f ~bc=b

On oldmatrix it shows flights.
On newmatrix it results in an error:



I tried to submit this using the feedback link, but it doesn't seem to allow attaching an already-generated screenshot, only capturing one at the instant, but the error dialog must be dismissed in order to click the feedback link.