Not accepting participant input to end trial

I have encountered a strange problem. I have a priming study with the following events: a fixation cross, a word prime, a blank ISI, a word target (with picture response labels) and then, following a participant response, it should move to the ITI and then the next trial. The picture response label is set to come on and end immediately but not clear the screen, so that it stays on with the subsequent word target. The word target is set to take input (the picture response label is not). However, the program does not take input consistently. Occasionally the participant response causes the trial to end, but most often the trial does not end when a possible response is selected. It appears to go out to it’s full time limit (1050 ms). Every so often, the trial seems to end abruptly on its own ahead of the time limit, which is very distracting (note, I have had this happen on other priming experiments, even when the program is taking participant input correctly).

The output file suggests that the program is taking the participant’s input. The RTs appear to be accurate. I have scaled the program down to just the practice block and it still has the same problem, so I’m attaching the scaled down version (along with the response label pic file). Help is appreciated! I can’t see anything in this program that would explain this odd error!

GSCT Priming Fa19_Practice only.sl5 (28.3 KB)

Response labels1.png