HL7800: Does +KCERTSTORE support PEM certificate chains?

I am trying to load a signed certificate containing two concatenated PEM certificates (leaf certificate plus intermediate) using +KCERTSTORE on an HL7800 running firmware 4.6.9.4.

The upload returns:

+CME ERROR: 930

The AT guide describes this as “Content of input data is invalid or not supported,” but I cannot find documentation stating whether multiple PEM certificates in one uploaded object are supported.

Does +KCERTSTORE require exactly one certificate per stored entry? For an mTLS client certificate chain, should the leaf and intermediate be uploaded separately, and if so, how does the modem associate the intermediate with the local client certificate during TLS negotiation?

does it work if you separate the certificates and store them in different indexes?

Actually I think you can also skip the intermediate certificate and just load the leaf certificate.