The update to watchOS 5 seems to have broken down swimming tracking on several Apple Watch models, with users reporting issues with counting laps and calories.
We can confirm the bug on the Apple Watch Series 2 and Series 3, as several units have been affected here at Softpedia.
Users discussing the unexpected behavior on Apple’s Communities board indicate the problem may exist on other Apple Watch generations, though the two mentioned above are most often impacted.
For now, it looks like the culprit is none other than the update to watchOS 5 released by Apple in September. After the update, the watch no longer tracks laps and calories accurately, showing insanely low figures for both of them.
“I have an Apple Watch 3, and just updated to WatchOS 5 yesterday. Today during my swim workout, the yardage counting is completely off - I swam 6500 yards, and it shows 100 yards. The calories burned are about 4-500 different than normal, the auto sets are completely wrong/missing as well as times and everything,” the topic starter estimates.
Recalibration could work
Users who have reached out to Apple support were being recommended to recalibrate the watch using the instructions here, but several have confirmed this workaround doesn’t make any difference.
For the time being, it looks like the issue is strongly related to the lap counter, which in its turn affects the burned calories estimates. The update to watchOS 5 may have reset the sensor configuration, and while re-calibration could indeed help, it’s not a workaround that may repair the issue in all cases.
Apple hasn’t acknowledged the bug until now, but the number of posts in the linked thread is increasing, and this is a sign it may be a widespread issue hitting more devices as they are updated to watchOS 5.
In typical Apple fashion, a fix could land in a future watchOS update, but until then, expect the company to say little to nothing about the bug.