Recovery time too long in FR945, compared to the metrics I had in FR935

Didn't have 935 like you before, but indeed, recovery time is always around 60-70 hours or so following a 2nhiura mountain bike ride. 

I wetn from an Edge 520 to the FR945 and for me the recovery time is about the same for similar activities and my feelings of tiredness.

After an hour of commuting on the bike I get, typically, 12-20 hours and after a time at the gym I can get 50 hours +

It's supposed to be based on HRV so are you using an HRM or the OHR? I would imaging the OHR to be inaccurate for any real activities of intensity?

How long have you had it? Could be a case of the watch still learning about you. The SW is updated compared to older models. I’ve always found the recovery guide to over estimate the time before you can do a hard workout. After you’ve been training for some time you know when to do a hard or easier workout anyway. 

Check your max HR setting on the watch, if it's too low it may think you're pushing harder than you really are.

Yet, if it too low, and marked as adjust automatically like in my watch, it will be boosted to the real value.

I bought it about 2 months ago.. it's enough time to learn

Generaly I use HRM Tri. 

I noticed the same when I switched from FR735 to FR245. Meanwhile I ignore that metric.

It is working great with me. Do you use the Heart rate strap ?

If not this might be the reason of misdata.

No, I always use my HRM Pro.