Could not post manual reaction after posting similar one

I tried to post the reaction "Hydrogen?" on an image in the TWIM room, after having posted and removed the reaction "hydrogen?" (note the lower case, although unsure it is relevant). The reaction did not appear on the event at all, not even a local echo. When looking in storage, it did make it into the pendingEvents store and even had a remoteId (`$-D285G1-z-DO-_PnqRuOgyVUv-IR1pqys45jPOEhWrE`) although it also did not appear on other clients. Trying again would have the send_queue give up with `already_annotating` in the logs.

I have logs for this bug. The remoteId in storage doesn't appear anywhere in the logs, which is weird.

Only after removing the pending event in storage AND refreshing the client could I post the reaction. (I tried before refreshing and it still didn't work, see 3rd log).

Start by reproducing the reaction flow described in the issue, then inspect the pendingEvents store and the send_queue handling that reports already_annotating. Use the available logs and the recorded remoteId to trace where the event stops being displayed or sent. Done means removing and reposting a similar reaction works without a refresh, and the reaction appears on other clients.

Written by the indexing model from the issue text.