This is a weird one: when running a simple script from an IDE, the viewer sometimes remains empty. I've experienced this repeated with PyCharm, and something similar has recently been reported by a Discord user using VSCode (discord convo).

I can reproduce with a certain reliability using this:

import time
import rerun as rr

rr.init("test", spawn=True)
#time.sleep(2)
rr.log_points("points", [(0, 0), (2, 2), (2, 2.5), (2.5, 2), (3, 4)], radii=0.5)

Uncommenting the sleep() call appears to reduce the rate of occurence.

I've never seen that when launching from the CLI, same for the discord user.

This resemble #2124, but is probably different, as the sleep call is before the logging call, rather than at the end. It's as if the viewer takes too long to start and the logged messages are dropped.