Repeatedly losing and re-establishing link to external power sensors

[Cy]

Two of my external power sensors have been repeatedly (multiple times per day) losing their link and automatically re-establishing it some time later - usually within a couple minutes, sometimes hours later. This only recently became an issue without any configuration changes and the tags all have fairly strong signals the rest of the time. Nothing I have tried has made a difference:
1) Recharge them, even though the battery level is well over the usual point at which they would need recharging
2) Changing the tag manager mode (wider, narrower - doesn't matter)
3) Resetting states
4) Calibrating frequency offset
5) Even migrating all tags to completely new wireless settings

Any suggestions?

Thanks,

Cy