If OP-TEE is used as SPMC, TF-A must be built using the flag SPD=smpd for it to implement the SPMD component. Since this is a generic component, it does not and cannot contain OP-TEE specific parts.
When paging is used, OP-TEE expects the loader to parse the "Header" section and load accordingly. This is done by the "opteed" component in TF-A which can not be used together with the SPD=smpd build config.
The current workaround is to point the BL32 build flag to tee-pager_v2.bin. This solution works as long as OP-TEE consists of this single binary, i.e. the pager is not enabled. Otherwise since only this single binary is loaded, booting OP-TEE fails as it cannot find the pageable parts.
The pager is not a must-have feature currently, but on longer term this issue needs to be addressed.
For background info see the op-tee documentation here: https://optee.readthedocs.io/en/3.9.0/architecture/core.html#partitioning-of-the-binary