Yes I have the clock sending to mine from the DT successfully. As you said, this is mostly used for the note repeat function. This works even with my MPD at the end of the chain of other devices…
MIDI Path: Digitakt OUT > Grandmother > EFX-500 > MicroFreak > MPD226 > Digitakt IN
Here are my settings, hope they can help.
MPD226
GLOBAL
CLOCK - EXTERNAL
DIGITAKT
SETTINGS > MIDI CONFIG > SYNC
DT Clock Send - ENABLED
SETTINGS > MIDI CONFIG > PORT CONFIG
OUT Port Function - MIDI
THRU Port Function - MIDI
INPUT FROM - MIDI
OUTPUT TO - MIDI
OUTPUT CH - AUTO CH
ENCODER DEST -INT+EXT
TRIG KEY DEST - INT+EXT
MUTE DEST - INT+EXT
RECEIVE NOTES - ENABLED
RECEIVE CC/NRPN - ENABLED