New tubeless setup: losing air through spoke holes

It’s my first time setting up tubeless. The tyre seems to have seated fine, but I’m losing air through three of the spoke holes when I go much above 20 psi. Details:

• new rim, new tyre (new bike in fact)
• 29" DT Swiss M 1900 Spline – tubeless ready
• 2.3" Minion DHF – tubeless ready

I’ve added more sealant (must be getting near 200ml now) and shaken it about, concentrating on the leaking areas; air has stopped leaking but that might be the loss of pressure – down to 10-15 psi I think. Will leave it to sit overnight at the lower pressure and see what happens in the morning when I add air.

But in my limited reading so far I haven’t seen this specific problem mentioned. Wondering if I’m wasting my time trying to seal this, and instead have a problem with the rim tape or even a defective rim?

EDIT: just for clarity – it’s a tubeless-ready rim, factory taped, which I’d have hoped would rule out any errors of tape selection or technique.