I have a transaction that doesn’t show up in the Android app, but it did affect the balance (and “spent today” on that day), so I know it went through.
When I looked it up in the API I can see “merchant: null” which seems to be the difference between that transaction and all the other spending transactions. It’s settled now, but still doesn’t show up in the feed.
There’s a similar thread here: Online Transaction affected Balance but didn’t show up on feed and in my case, this a newly-opened local food court, so I guess it fits in with the observation about smaller retailers.
Any plans to fix this? You could just put a placeholder transaction up - or even an error saying “merchant missing” or similar. There is a “description” so that would be useful info to see.