Apple Health - extremely long delay between step updates

Over the past couple of weeks, I've noticed that the Health app will now only refresh the steps counter every 10-12 minutes or so. Disappointing enough, but not disastrous. However, since yesterday's upgrade to iOS 18.0.1, the delays have become much, much worse: over two hours, then another three hours after that. This is plainly absurd.

What's going on? Is this the way it is with the new upgrade, in a push for more battery life?? Is it now designed to update only if movement is detected? If I've been out for a hike or a run, and lay the phone down, it's as though the clock freezes at that time, and will only update once it senses more steps.

Even more infuriating, when it does eventually refresh, the update is already 12 minutes out of date: right now my phone clock tells me it's 16:16, but the steps 'update', seconds ago, says 16:04...??

This has, for me, rendered the app utterly useless. Any assistance (or suggestions for another step-counting app) will be appreciated.