A "default.png" image briefly appears during time lag (~0.5 s) when loading images on Pavlovia experiment (initial trials only)

URL of experiment: Pavlovia

Description of the problem: An image that contains alternating red and white “default.png” text in diagonal orientation appears about 0.5 seconds before my actual, uploaded images appear. I am not sure what is causing this default.png image since it is not one of the files in my image folder. This default.png image only appears in the first trial of my “practice_trials”, and for the first trial of my “trials” loop.

There does seem to be a slight lag for loading images between trials. The images from previous trial appear for about 0.5 seconds before switching to the images of current trial, so perhaps for the initial trial (because there was no previous trials), the default.png image appears during that time lag instead of the previous trial’s images.

Please advise as to what the default.png image is, and what to do about the time lag?

Note: The same experiment works without any problems locally on PsychoPy.

@TParsons This could be related to this: afterimage in variable-based setting of image components in loops - possible bug in exported PsychoJS Code from Builder · Issue #5644 · psychopy/psychopy · GitHub