[Bug] Backfill from G7 Created Bad Data

[dmccurry]

Describe the bug
G7 data that was backfilled appears to have incorrect timestamps, which is leading to bad future data.

Attach an Issue Report
Loop Report 2025-03-04 22:57:27-04:00.md

To Reproduce
N/A - Seemed to randomly happen

Expected behavior
When data backfills, it should have timestamps that are not in the future.

Phone

• Hardware: iPhone 15
• OS Version: 18.3.1

Loop Version

• Version Number: 3.4.4

CGM

• Dexcom G7
• Dexcom App

Pump

• Omnipod Dash
• Firmware version: 4.10.10 (BLE Firmware 1.4.0)

Additional context
No matter what I try I cannot get this data purged. I'm thinking because it's missing the uuid it cannot be deleted, but I'm not sure.

If you look in the attachment, this seems odd:

* 2025-03-03 22:50:21 +0000 G7CGMManager DXCMmT receive Sensor didRead G7GlucoseMessage(glucose:Optional(128), sequence:34 glucoseIsDisplayOnly:false state:ok messageTimestamp:9531 age:6, data:4e003b250000220000010600800006fe76000f)
* 2025-03-03 22:50:22 +0000 G7CGMManager DXCMmT receive Sensor didReadBackfill G7BackfillMessage(glucose:Optional(202), glucoseIsDisplayOnly:false timestamp:855194, data:9a0c0d00ca00060f0c)
* 2025-03-03 22:50:22 +0000 G7CGMManager DXCMmT receive Sensor didReadBackfill G7BackfillMessage(glucose:Optional(193), glucoseIsDisplayOnly:false timestamp:855494, data:c60d0d00c100060f00)
* 2025-03-03 22:50:22 +0000 G7CGMManager DXCMmT receive Sensor didReadBackfill G7BackfillMessage(glucose:Optional(186), glucoseIsDisplayOnly:false timestamp:855794, data:f20e0d00ba00060ffb)
* 2025-03-03 22:50:22 +0000 G7CGMManager DXCMmT receive Sensor didReadBackfill G7BackfillMessage(glucose:Optional(130), glucoseIsDisplayOnly:false timestamp:8925, data:dd2200008200060ffe)
* 2025-03-03 22:50:22 +0000 G7CGMManager DXCMmT receive Sensor didReadBackfill G7BackfillMessage(glucose:Optional(116), glucoseIsDisplayOnly:false timestamp:9225, data:092400007400060ff5)
* 2025-03-03 22:50:22 +0000 G7CGMManager DXCMmT receive Sensor didReadBackfill G7BackfillMessage(glucose:Optional(128), glucoseIsDisplayOnly:false timestamp:9525, data:352500008000060ffe)

The first three backfills are timestamped ~10 days ahead. This could very well be an issue with Dexcom, but wondering if it's come up before. Thank you!

[dmccurry]

The other side effect of this is I'm not able to find or delete the erroneous entries in Apple Health, but they're still present in Loop.

If this is a one-off with just weird sensor data it's probably not a bug. The other three entries given were correct values.

I'd be happy to help out with a fix if doing something like "if backfill data is in the future, we should ignore it" is an option.

[marionbarker]

Sorry not to respond earlier. Were you able to resolve this? If so how.

[dmccurry]

The only way I could resolve (other than waiting 10 days) was to wipe the phone and reinstall loop.

[marionbarker]

Closed with Loop 3.6.0

[jwoortwijn]

I've experienced this bug in 3.6.0 as discussed at https://loop.zulipchat.com/#narrow/channel/148543-Loop/topic/Loop.20failing/with/520219077

iPhone SE 2020, iOS 18.4.1 Loop 3.6.0, Omnipod Dash, 4.10.0, 1.4.0. Dexcom G7.

Exporteren 20250524T190001Z.zip

ETA:

Loop Report 2025-05-25 080505+0200.md

[marionbarker]

@jwoortwijn Would you please post a Loop Report as well.
Got to Loop, Settings, Issue report.

[jwoortwijn]

@jwoortwijn Would you please post a Loop Report as well. Got to Loop, Settings, Issue report.

Done, edited my post.

[jwoortwijn]

Deleting and reinstalling worked. I did not need to wipe the phone.

Thanks for your support, hopefully you can find the bug.