[PsychoPy 3.2.4] core.wait corrupts win.flip duration

Coding
,
1

Dear all,
I am using PsychoPy 3.2.4 (StandalonePsychoPy3-3.2.4-win64) coder. It runs on a 60Hz Dell laptop.
The time distance between 3 win.flip is about 50ms. in na minimal code (given below), it works. But once I add core.wait, the next flips will drop/shorten/else, which will result in 3 flips lasting about 22ms (still on a 60Hz…). I tried on a more recent version of PsychoPy and this issue seems to have been fixed.
Anyway, can someone explain this bug? Why it happens and what’s the function caracteristic that produces this bug? (to look for other erronous timing).

import time
from psychopy import core, visual, monitors

def reset_clock():
    global start
    start = time.perf_counter()
def get_latency():
    print("Elapsed time: {:.2f} ms".format((time.perf_counter()-start)*1000))

win = visual.Window(fullscr=False, monitor="testMonitor", size=(480, 270))
for trial in range(10):  # make multiple tries 
    core.wait(.2)  # <<<--- TROUBLEMAKER: core.wait function --->>>
    win.callOnFlip(reset_clock)
    for _ in range(3): 
        win.flip()
    win.callOnFlip(get_latency)
    win.flip()  
win.close()
core.quit()

I appreciate any help.