Slack Integration - Messages sometimes not appearing in Slack?

Hi guys,

Apologies if this has already been posted, I couldn’t find anything completely relevant (I saw a thread about a new 2018 feature but I don’t know if this is related). Over the past few days we have noticed that some alarms are not triggering sentry alerts in the channel: There are two projects in particular I have which are exhibiting this strange behaviour. One is not sending at all (but the test button does work), and the other sends probably about 50% of the time.

Is there away of finding out if there is issues with this?

Best Regards