120fps bottom layer png of car, duration 120frames, top layer png of indicator lights duration 60 frames, run movie lights flash. GOOD !
select both layers and go Modify>convert to symbol>movieClip. Copy the MC that appears in the library to a new blank file, make that file also 120fps. run movie see car but no lights flash.
I have done no coding at all, does it need such to run. It has just what may be created when choosing new file.
What I had been doing was putting this MC at the start of a bent line, snapping to the seed point, then 7 secs later (frame 840) placing it at the end of a bent line, snap etc, rotated it to match direction of line, created then a classic motion tween, then added a guide layer and put this line (edit copy>edit paste in place) onto that guidelayer at fr1. deleted the original line. Made the MC at fr1 orientToPath. Run Movie and it worked, but no indicators. Thinking the indicator function got screwed up somewhere, I did the test above. Obviously not the MC as a classic tween at fault. Something fundamentally basic I am expecting to work.
If you convert to movieclip on the main timeline, the two layers was probably combined into one layer/one frame. You can double check this by double clicking the movieclip inside the library. You will probably see only one layer with a single frame instead of 2 layers with one at 120 frame and the other 60 frames. To get around this, create a new symbol (Insert > New Symbol). Copy and paste the frames from each layer into the symbol.