Encoder initialization error with SSI / SinCos encoder on XG21 (secondary encoder)

I am working on a project which uses a belt driven linear axis and a ctrlX drive (XCS2-W0023). The linear position of the axis is measured through a secondary encoder (IMS-C absolute with SSI and SinCos). We upgraded the drive firmware to 06V04 to allow the configuration of the secondary encoder with both SSI and SinCos (encoder type 26). We setup the encoder best we can by copying the configuration parameters from a working IndraDrive setup to the ctrlX. But we have not been able to get the drive operational. We got the following errors:

https://docs.automation.boschrexroth.com/doc/2919662806/c1108-encoder-basic-error-during-encoder-initialization-xg21-x-y/latest/en/?ivpp=ID165941_214128035&inTopicJump=C1108

https://docs.automation.boschrexroth.com/doc/2053370437/f2042-encoder-2-encoder-signals-incorrect/latest/en/?ivpp=ID165941_214128035&inTopicJump=F2042

As a workaround we setup the drive with SSI only.

We can also run the drive with the encoder setup as SinCos.

Only the combination SSI / SinCos does not work.