V20.2.1 (Beta) - stranding SM with V16 firmware?

We have upgraded a number of AP to V20.2.1 (Beta1 or Beta2). We have some SM in the field which were not upgraded since the SM was off (owner on vacation or has been turned off for non-payment).
Now we are having issues when they are coming back and being rejected since they don’t support multigrant.

The CBRS log in the AP looks like this

04/30/2021 : 15:34:19 UTC : CBSD is already registered with SAS
04/30/2021 : 15:34:19 UTC : Disabling multi grant mode since radio is not capable
04/30/2021 : 15:34:19 UTC : Requested operation parameters cause too much interference in the CBRS spectrum.
04/30/2021 : 15:34:19 UTC : SAS Error : Rejected due to PAL incumbent
04/30/2021 : 15:34:19 UTC : [0] Too much interference caused by the device for other users, hence grant rejected
04/30/2021 : 15:36:19 UTC : Failed to send Grant request [Err: CBSD_SUCCESS] after timeout

tried to edit the SM for power etc but that has not worked.

We have 23 other SM on this same AP in various EIRP powers working fine. We have other AP with V16.2.3.1 SM and they are working fine in Widegrant status

Since the SM can’t log in, it seems our only option is a truck roll?

Based on the information you provided here, an upgrade of the problematic SM’s and a conversion of them to multigrant may not help. The particular error code you are getting suggests you are likely not going to get at least a portion of this grant request accepted by the SAS due to another operator’s PAL. Although multigrant could allow for a subset of your request to be granted by the SAS for this SM, you can’t operate the SM at a lower overall Bandwidth than the AP is transmitting at, so multigrant wouldn’t help in that case. My suggestion would be to open a ticket with Cambium support, if you have not already, to have them take a closer look. They might be able to help directly, or may redirect you to the SAS vendor for a full answer.