Dexcom readily Calibrates Downward but not Up

I had not noticed this too much before this year with my G4 receivers. It seems that when the meter BG is entered Lower than what Dex says it will regularly calibrate toward the entered value. However, in several instances if the entered value is higher than Dex it does not want to come close to the entered value. This is particularly noticed after day 5 on a sensor. Does anyone noticed similar behavior?
Most recent instance was last night on day 11 of a sensor, day 4 after restart of a receiver and yes the sensor was near failure with 3+ hours of ??? earlier in the day. Receiver was constantly reading LOW and in the 40s. 1st entry near 90, dex climbed into the 60s. 2nd entry near 90, dex dropped into 50s. 3rd entry around 90, dex stayed in 50s. Each entry was 16 and 17 minutes apart.
This morning Dex was reading 20 less than entry and again refused to re-calibrate. Tried only 1 time before changing sensor. Forgot to shut down this receiver and tonight it is reading very close after a single cal (with the new sensor) resulted in a drop of 25.
Even if the sensor was failing, I would have thought dex should have re-calibrated when the raw data from sensor was fairly stable.???
Is the 3 stick recal supposed to be at least 15 but less than 20 minutes apart?
From what I understand my dex software should be as good in G4 as is the G5.

If the sensor didn’t fall into compliance on the 3rd calibration you should have called Dexcom to get it replaced

Not when it was beyond it’s 7 day guaranteed life (day 11).
Still wonder about the refusal to readily calibrate upwards. Perhaps a security to avoid entering bad high value if a stick was wrong? Only 1 other set of equipment that I have calibrated many times, often with great difficulty - navigational fluxgate compass that was not meant to be moved from boat to boat.

Ah. I must have been low when I read your post. LOL (ie, I know the warranty is for 7 days)

I have not noticed this behavior at all and I really doubt I’d miss that if it happened.

Still wants to calibrate lower than meter reading, typically around 10-15 lower. Seems to agree fairly close toward sensor day 6 & 7 as well as after restart of same sensor.