My first thought was the wavetable header volume, maybe there is some mixer/configuration software where you can check it's not very low or zero?

Try Aux B level or similar in the mixer.

I‘ll check the mixer when I get back home in a week.

Are you running the initialisation software for midi for that soundcard? I know that my ESS ES1868 (or maybe 1688, can't remember) won't give any MIDI output until it's run that in DOS. I remember having a similar issue to what you're seeing and having to spend a while figuring out how the card is supposed to be set up in DOS, I think it's ESSCFG.EXE.

You could try testing it out in Windows instead to see if that helps, since once drivers are installed in there, it should initialise MIDI in Windows just fine. You can select MPU401 output in the Multimedia settings and that will output to the Dreamblaster.

If you try that and it also fails with a known good MIDI / waveblaster header setup - which is probably not your problem because yours works with a CT2230, another issue I had with mine is that I somehow blew the component that handles the MIDI input serial data. I was able to work that out because it would work over USB but MIDI input on the waveblaster header did not work. That's less likely to be your issue but I do recommend testing out USB MIDI to see whether that works as a last resort.