We have had problems with integrating the SE5K into the Victron system from start (installed in May-25). It has been working short periods on some 3.64-betas, but been lost again a couple of days later. Now it will not come back when performing a reboot in Venus OS.
With the current official release of 3.64 the SE5K-inverter is not shown. Nor is it in latest beta 3.70~25. Another system with an older SE-inverter running on the latest beta is working perfectly.
The one we have working is the old model with the lcd display. I guess it is running an old firmware. The one not working is the newer model without the display. It also have the latest firmware installed.
They are on two different sites, so we are not having the same issue as you have.
What models are you running? Can it be that the lcd-version is easier to get to work than the newer model?