Beginner question: drawing artifacts while debugging?

Hi – I’m logging temperature readings in an array, and drawing them to a graph on a screen periodically (using TFT_eSPI), one line segment at a time.

When I run the debugger (via ESP-PROG) everything still basically works, but I notice that if I set a breakpoint right before I do a temp reading, and the execution pauses there, and then I continue execution, the next line segment being rendered to the screen get a little gap at the start: meaning, roughly one pixel is missing at the start of the line segment.

I can’t think of a reason why this would happen – nothing in the code is time dependent in a way that would be relevant, so the pause and the resulting timing shouldn’t matter to the drawing coordinates or interface with the drawing library at all (and the breakpoint is happening well outside of all graphics calls.)

So I’m scratching my head trying to figure why this might be happening.

Can a long pause on a breakpoint mess up SPI communication in subtle ways? If the first SPI communication after the breakpoint didn’t come through or was corrupted somehow, that might explain it: I believe the first thing the drawing function does is read a pixel from the screen’s buffer (in order to anti-alias properly over the background it’s drawing on top of), so if that got corrupted it could explain these little dropouts.

Is this a pattern familiar to anyone? Thanks!