Interop US915: Too many uplink packets to validate test

Interop US915: Too many uplink packets to validate test

We are having difficulty running the N° test without a hitch. It works once in 4 or 5.
We often get the error: "Too many uplink packets to validate test" See screenshot below.

Note that we know that one of the frequencies is not listened to here (903.000MHz 500Khz).
Indeed the LinkADRReq of the test positions a ChMaskCnt there 0x5 and redundancy at 0x3 or 0x53.
We only have a single Gateway Pico 915 listening in 8 bands 0 to 7.
So our LC64 uplink must be lost (903000 500KHz).

So questions are:

What is the link with the error message obtained (Too many uplink packets to validate test)? 
How many reception anomalies (only 2 frames out of 3 for an fCount) can the test tolerate?

Best regards
Pierre-emmanuel