This will be due to 3.15.0’s dropping of the use of server provided activity type models, and should be temporary (hopefully only a few days at most).
Arc works out what activity type to assign to recorded samples by making use of three levels of activity type models:
- D0 model: A single global model
- D1 models: City/state sized models
- D2 models: Neighbourhood sized models
When a new sample is recorded every few seconds it gets passed to those three models (with the relevant city and neighbourhood models loaded, if available), and then the combined results of them are used.
For years now, Arc has built personalised D2 models on your phone, based on your confirmations and corrections, so that the results are personalised to you, your activities, movement patterns, locations, etc. For the D1 and D0 models however it relied on server provided models that were the result of everyone’s “correction sharing”, providing generalised results as a fallback for cases where your personal D2 model either didn’t exist yet or didn’t have enough data yet to be accurate.
Since 3.15.0 Arc no longer uses server provided D1 and D0 models - it builds its own on-device. So all of the activity type classification is based on your own personal data. This makes the results much more accurate, and also removes the one remaining server side component of the app. A big win. (Thanks @Astra for making this happen!)
The catch is that initially your Arc install won’t have your personalised D0 built yet - it’ll take a day or two to get built overnight, depending in iOS’s mood. It also won’t have your own D1 models for each city/state area that you have data for. Again, those will take a day or two to be built overnight.
What’s probably happening in your screenshot is the D1 model for that city region hasn’t been built yet (and maybe even the D0 hasn’t been built yet, from the looks of those oddly bad classifier results). So it’s probably a case of iOS being a bit of a dick and not allowing the nightly model updates task to run to completion.
Typically though iOS isn’t enough of a dick to stop any backlog in that task eventually catching up. So it will self correct (and typically it should be all done within a day). If you only updated to Arc 3.15 recently, that could explain.
But if you’ve been on 3.15 for a while now, it might be worth installing Arc Mini, if you haven’t already, and have at the System Debug Info in there, to see what’s going on. In that view there’s a row for “ActivityType models pending update”. That’ll show you a list of models that’ve been marked for update and waiting for the nightly update task to run.
If the list only has maybe less than 10 models in it, then all is well and it’ll probably get through them by tomorrow. But if the list has many tens of models, then it might take longer - a bit of a backlog.
Aside: The updates task always first picks out the models for the region you’re currently in, updating those first, to make sure that even if there’s a backlog, at least the models needed right now are up to date.