I still don't have my keyboard online to test - so maybe the MODX Template already does this. But have you tried changing your MIDI channel (on each track) to "Any" as suggested:

You can correct it by doing one of two things:
1– If you want to record all four, set the Cubase MIDI Track so the Channel is “Any” (this echoes the data back on the Channel it came in on)

Right now the last screenshot I believe has these set to MIDI channels 1 through 16 (... or your last track number) depending on the track.

I guess you could sort out your MIDI input independently from the output and turn off all MIDI outputs. Then just try to get the MIDI activity and monitor to show MIDI activity "forever" (for as long as you play) without trying to deal with the return path for MIDI at first.

I reread the article on setting this up, and maybe I don't understand or it's a different workflow. But it was suggested to have the Any setting on One track and then Dissolve the Midi Parts later (by channel) for editing. I did try the Any setting and it does the same thing with my midi (cuts it off).

One thing is, like the poster in another thread about setting this up, I like my midi channels separated so I can tweak them as I go. Also, when I use the Template, it sets up several Midi Tracks and gives them different channels (which is the way I want to work anyway). However, when I do get Midi activity, it is spotty like before.

I guess you could sort out your MIDI input independently from the output and turn off all MIDI outputs. Then just try to get the MIDI activity and monitor to show MIDI activity "forever" (for as long as you play) without trying to deal with the return path for MIDI at first.

Not sure what that means. Wouldn't I need Midi output so I can hear what's going on? maybe I don't understand, but if local is off then the midi needs to come back to the keyboard so I can hear it. Does that sound right?

This is what you already know:

... activity. The MIDI activity monitor on the transport control shows the same thing.

So, no, you don't have to hear anything to know the MIDI behavior has changed since you already have confidence that a visual indicator matches what you hear.

There should be a mechanism to monitor MIDI visually. Even turning on record for the track and seeing MIDI track fill with data or stop at some point as it does now.

Not saying you have to do this - but you can break apart the problem working one direction at a time.

I've enclosed what it sounds like when I play so maybe there's more information to go on.

I recorded the sound from my headphones sitting by the keys, so you can hear when I'm hitting the keys.
I first hit about 30 1/8th notes, you'll notice some sound comes out some doesn't. There's what sounds like a half note or so near the beginning, but I am hitting 1/8th notes the entire time. Then at the end, I play 3 whole notes (about 4 beats), holding the key the whole time. The first hit/press no sound comes out, the next two it comes out, then stops after a couple/few beats (not exact beats or timing), not the whole time I'm holding the key down.

Hope this helps. I'm still trying things (reboot, taking out and replacing drivers, checking cables, different configurations...)

Not that it matters much (because we already believed you had an issue) - but I'd probably start with something like "CFX PopStudioGrand" which is a single-PART Performance and would have a familiar sound to everyone with familiar programming and response - that is, if I was sharing how something sounds. None of us are quite sure what your custom Performance is supposed to sound like but I can easily get on the same page with "CFX PopStudioGrand".

Make sure ARPs are turned off and motion sequence is turned off.

If you're having lots of crazy issues it's best to start small and build up. Start with a 100% factory preset and something that has no ARPs or motion sequence. Something "plain", "small", "simple".

Here's a simple Init Multi/GM with only piano. Lots of 1/8th notes, and some whole notes. I verbally say when I release the key on the whole notes.

Quick easy test... do the same thing NOT connected to Cubase.
Be sure to use “Quick Setup” = Standalone.

Bump. If the instrument has no problem in Standalone (not connected to Cubase at all), you can conclude it is in the routing/connection with the software.

Sorry I haven't responded, Haven't had time to mess with this. I will try what you said.