Advantage AP upgraded to 8.1.4 from 7.3.6

We discovered an issue with a the 5.7 Advantage AP’s that we upgraded from 7.3.6
We found that the link tests will be about 30% of the “normal” rate and still show 100/100. (AP dl is 70%)
All customers registered to that AP show this symptom. When forced to an adjacent AP the link tests for the same customer are as expected.

Both tested devices are current 8.1.4 and managed via prizm. We have @ 80 AP’s in service and we have only found this issue on 2 so far.

Once you downgrade back to 7.3.6 the customer rates go back to normal (30%u / 70%d) and throughput rates correspond with the customer experience.
Has anyone else noticed this issue?

We tried to reload the 8.1.4 and the result was the same on the AP’s in question.