What Blast Cult did you get?Each of my fretless basses (all unlined) are *slightly* different so foe me a lot of intonation is muscle memory. This was never more apparent to me until recently. The Blast Cult I got is 32" scale; everything else I have is 34" with similar neck profiles. The BC is not a massive adjustment, but it's still an adjustment. I'm at the point with that bass I have very few clams now but that was a month or so of using that more than anything else.
The other thing I've found with fretless over the years is practice the simple stuff. That's what's helped make my intonation fairly solid. I still go back and do things like whole/half notes, octave stuff, etc. I try not to get lazy.
Agree that good equipment and clarity (i.e. being able to hear yourself) is a crucial element of playing in tune on fretless, but to me, it's more than that. In band situations it's the ability to hear myself; it's one reason I got rid of the PJB Double Four; I found it muddy with the RA D4.
I checked their website, but the aesthetics don't call out to me at all.