Same issue for me, my wife and son. We removed the AirTags shared and then reshared again. The AirTags in my Find My that i shared with them won’t show my AirTags location to them. The AirTags they shared with me do not show location in my Find My. Some issue with shared AirTags location. This started last Friday December 8th.
Apple support told me that this is a known issue and they are working on to fix it with next iOS update. I don’t know if she meant iOS 17.2 or iOS 18 though.
iOS 17.2 will release soon and lets see, if that fix the issue or else, in future updates. I wish apple proactively publish this, so that customers are aware than calling apple support.
Refer to following thread too:
Shared AirTag No Location Found - Apple Community