On my line, after 3 days, the DLM resynced the line and removed interleaving.
However, it's still not in the same state it was before G.INP syncing 5Mb below what it did before and it's also resulted in a stuck bt profile which is making it over 10Mb slower than when G.INP started.
I've tried disconnecting the line for 40 minutes, now twice, to unstick the bt profile. My ISP doesn't seem to know what bt profiles are telling me that the only thing that limit line speed is the sync speed! I hoping my ISP, Plusnet, will get this sorted at some point. :-)