I had an issue establishing links with XS+31LC10D module, and got an info from support stating that for:

XS+31LC10D
XS+2733LC15D

modules, the following settings need to be applied when plugged in to SFP+ interface:

/interface ethernet set sfp-sfpplus1 auto-negotiation=no speed=10Gbps full-duplex=yes sfp-rate-select=low

"In order to establish 10G links using 10G/25G optical fiber transceivers, an additional SFP Rate Select setting must be configured to avoid data corruption during transmission."

Didn't fid this elsewhere, maybe it will be useful to someone else.

EDIT: Apparently, there is a WIKI on this topic (but I couldn't find it): https://wiki.mikrotik.com/wiki/MikroTik ... ansceivers