DT Swiss 11 S Road & MTB cassette – spacer?

I’ve a pair of DT Swiss G1800 gravel wheels (3 pawl 370 hubs) & I’m pretty sure that the freehub was marked 11 speed road. I built the bike up with a GRX 400/600 2×10 groupset & a Deore 11-36 MTB cassette. I assumed that I’d need a spacer (confirmed by Wiggle) which  I’ve fitted behind the cassette (as with my Swift’s Hope Pro 4 wheels).

All seems fine & the lock nut is nice and flush at 40Nm & rear mech. set up was easy & trouble free. All good.

However, there are some issues at the front.

In the small ring I can ride all the cogs in the low position without rubbing. There’s no movement into the Low Trim position because the low limit screw prevents it (Low Trim isn’t needed). However I am struggling to dial out all rub in the high gears (big ring & smallest few cogs). There’s space from the cage, but under load the chains catching the plastic insert.

I’ve been wondering whether, if the cassette was a few mm inboard (the spacer wasn’t there) I’d be using the Low Trim position & have a bit more wiggle room with the high gears.

I’ll pop the cassette off at some point and double check that it is an 11 speed road freehub, but assuming that it is, I assume that I do need a spacer and that it need s to go behind the cassette?

Do you perhaps need to adjust the front mech in its current position so the low trim can be used? Low trim is just a function of cable tension isn’t it.

If it’s a G 1800 then yes it will be a 11-speed Road HG freehub.

Thanks, so it will need the spacer behind the cassette then?

I’ll have a look at the front mech. adjustment too, I may just be being cack handed.