Events going missing from incremental /syncs

[ara4n]

I've had several instances in the last 4-5 days where messages and/or state have gone missing from my clients. It's unclear whether these are clientside or serverside bugs, but in combination with #7083 and #7065 i'm wondering there are synapse-side regressions going on.

These have all happened in v5 rooms, as far as I know.

Concretely:

• https://github.com/matrix-org/riot-ios-rageshakes/issues/3976
• https://github.com/matrix-org/riot-web-rageshakes/issues/2375

Also, element-hq/element-web#7843 seems to be a grabbag of "my client got out of sync with the server somehow". However, some of these seem to be "a chunk of my history went missing" and i don't know why - which could point at synapse providing unreliable sync responses.

[ara4n]

Conclusion: i'll look at the rageshakes to try to infer whether this is clientside or serverside before team synapse looks further.

[richvdh]

going to close this pending further info.