HR zone 4 93-95%

Wow that is a very narrow band for Z4. 

The bands around it are much wider , so I suspect that is the route cause. Maybe consider widening Z4 a tad?

Also do you have a specific Sport Heart Rate set up?

Sometimes these bands get "changed" during an updated "inadvertently" also.

Were the bands the same in prior activities (looking at those old activity charts)

My Z4 is "threshold" and set to 94-100% of LTHR.  

you can adjust them manually in your watch under Settings>User Profile>Heart Rate & Power Zones,,,,

Understand- that there is nothing magical or perfect about zones.  they're anything you or your coach want them to be.  Training Peaks uses 10 zones.  Most Exercise Physiology studies use 3 zones.  I think Jack Daniels used 4 zones.  

these aren't specific break points in your physiology. Think of it more as a dimmer control than a light switch.  The zones are there for however you want to track and partition your intensity, and are very useful for managing training load.  

And- while your MaxHR won't change (much), your LTHR can move a lot, and it's best to have your zones set as a % of your LTHR- and, different for running and cycling.  so, either manually manage where it is or let garmin calculate that for you- but- I'm not impressed with Garmin's accuracy on this, but it's better than nothing if you don't know your LTHR.

But- bottom line is- if you're here, and your taking notice of your zones... then you're ready to start really thinking about how you want your watch to calculate these for you.  it's your choice.

I toggled it today to %Max HR and then back to LTHR and it seems to have reset the zone(s) to normal looking ranges.  No idea what happened but we're good again.