Lens correction no longer works for Camera Roll imports (LR 7.2.1 on iOS 15.4)

Lightroom 7.2.1, iPadOS 15.4, on 5th gen. iPad mini.

Lightroom 7.2.1, iOS 15.4, on (yes, ancient) iPhone 6s.

Both devices have the same issue. All photos are taken on the iPhone, none on the iPad. The Enable Lens Corrections toggle no longer works for photos imported from the iOS Camera Roll. From past experience, I expect to see a slight bulging-out to fix the iPhone camera's pincushion distortion. I started noticing this today, so it's unclear to me if this is a problem with LR 7.2.1 or the recent iOS 15.4 update. The problem occurs on all photos taken with Apple's built-in camera app, regardless of the iOS version associated with the original image. Photos taken with the LR app can still be corrected, again regardless of the LR or iOS version associated with the original image. Lens corrections applied to Camera Roll imports before the udpates (that is, both import and correction were performed prior to LR 7.2.1 / iOS 15.4) remain corrected. I don't have any uncorrected old imports, but un-toggling that switch for previously-corrected photos doesn't return them to their original pincushioned state.