I don't have a great solution for that, really, other than ensuring that updates are highly visible in a room where people are likely to read them and have a good culture around helping folks.

I've been in environments like the one you describe, and I think at the end of the day it's more of a cultural issue than something that can be solved using a tool.

this ^^^^^^^^^^^

I get around it by pinging people directly (usually I reply to my question as a thread in Slack and @-mention them, so the main channel doesn't get cluttered with my reminder) if a couple hours go by without a response. Still usually faster than waiting until the next day to ask at standup.