ePMP 3K not grouping customers

I am having some issues with one of our 3Ks with Cambium dual-horn antenna (all devices running 4.6rc35) not grouping customers. The issue was present 4.4.3, 4.5.4 and 4.5.6. The customers are very close to each other (in some cases next door to each other), but they show no groupable SMs. Attached are screenshots of the map and wireless pages. In the wireless page screenshot, the two with blue marks next to them are right next to each other.

This is an expected e3k behavior.
MU-MIMO grouping depends on angle diversity between SMs. If SMs are clustered in some area they are not groupable. Refer to the following topics for detailed explanation.
ePMP 3000 4x4 MU-MIMO performance - Knowledge Base / ePMP - Cambium Community (cambiumnetworks.com)
ePMP 3000 MU-MIMO grouping Criterion - Knowledge Base / ePMP - Cambium Community (cambiumnetworks.com)

The more clients you add, the more options there will be for the AP to group them. However, if they are two close to each other left-to-right, then those can’t be grouped with each other. In other words, if they are all in a nearly straight line from the AP

There needs to be a bit of an azimuth spread, which typically will happen with a natural spread of client as the AP loads up with more and more SM’s. Most of our AP’s have the clients grouped with over 1/2 of the other clients, so they are capable of MU-MIMOing quite often.

Even on of our new, lightly loaded 3000’s with only 7 clients currently - they all show 3 or 4 groupable partners, and at time, the MU-MIMO data hits nearly 100% of the total TX data.