I'm using an LXD75 mount, ZWO ASI462MC camera for guiding, and a Nikon D5300 for imaging. I have most features working well and guiding in particular has been really solid for me.
The one issue I'm having is with the alignment module. This then means I can't use the scheduler, automatic meridian flips, etc.

I think the module is doing what is promises to do, that is, it:
1) Grabs an image successfully
2) Plate solves accurately (and quickly!)
3) Syncs the mount
4) Requests a new slew.

The problem seem so be that once it's within a few hundred arc seconds, the LXD75 mount just wont' respond by slewing any closer. It seems it decides it's "close enough" and just stays put. This leaves the desired target either at the edge of the frame or just off frame.

At this point, I bring up the manual controls in ekos and use them and repeated plate solving to dial in the right location manually.

This could still be automated if step 4 above was changed to

4) If error > X, request a new slew. If error < X, send guiding pulse of length to correct for error.

Is there any chance this is already possible and I've missed it?

Could you clarify what you mean when it just stays put - does it keep trying to slew and platesolve but doesnt get any closer or is this something else?
In my case I have noticed there are times the align module does the former and I have to stop, slew the mount to a different point and get it to align again. But that problem seems to be related to my mount, not due to the software.

Yes, exactly, it keeps trying to slew and platesolve (since it correctly realizes that it is well above the specified error threshold) but eventually just stops getting closer, even while still several hundred arc-seconds away.

Note that when even further away, it does get closer, but then eventually it stops making progress. Unfortunately the error it can't improve upon is enough to put a target off or nearly-off frame.