I can't work out this, I chalk it up to yet another mikrotik bug

I have 2 routers in our network that just refuse to bring up a VPLS tunnel now. They were working fine, then suddenly out of nowhere they just flat out refuse to connect to each other. And I can't for the life of me work it out
Before we get to that. for the last 2 days 1 of these routers loses almost all its VPLS tunnels and the only 'fix' is to reboot the router. I suspect this is a bug introduced in a later firmware, but I don't know what the previous firmware version was to revert back to it. So if there are any known MPLS/VPLS issues introduced since at least 6.43.x upwards, please let me know and I can try downgrading

The link is A->B->C->D
A and D will not bring up a VPLS tunnel, at all, it never enters the running state
Currently all routers are running 6.45.8 (latest bugfix)
All routers run MPLS, all have MPLS MTU of 1538, all radios between routers can carry at least 1700 bytes so not a L2MTU issue
All routers have valid /32 routes advertised by OSPF
All routers have what looks to be correct MPLS forwarding table entries
When doing traceroutes I can see MPLS is used
Everything looks perfect, yet VPLS does not come up. Can't figure it out

What other troubleshooting can I do? Even restarting all routers in the chain does not help, A and D don't bring up a tunnel. Yet I can send pings over MPLS just fine

edit: after posting this I made test tunnels from A->B and A->C as well (B->D and C->D already exist). I made the tunnels and noticed that the one from A->D came up on its own with no other changes. When I removed the test tunnels, A->D dropped, but came back up again on its own. So I think there's some weird MPLS issue happening
This is not good enough for me. I need those tunnels to be reliable, I can't just randomly do things and reboot routers hoping it works. And it has been working for months before.....

Really need help with this. Downgraded all routers in our network that were on 6.45.x back to 6.44.6 and still havn't the same problem
Various tunnels (completely different locations this time) are just going down and not coming back up. This is a huge problem

I've put in half a dozen EoIP tunnels for now as a workaround, but this is not suitable
To recap,
OSPF - working perfectly
MPLS - seems to be working perfectly, traceroutes show MPLS tags

Can you post configs for all 4 routers in the A,B,C,D chain and the output of the following on A and D?

it seems like to me OSPF issues

We have started having the same issue since going to 6.46.2 from 6.44.5
The link between two routers goes down then comes back up. The OSPF then re-establishes fine then 2 of the 5 VPLS links will come back up. The main one luckily that comes up carries all internet traffic but the voip and network management VPLS does not. To re enable all I need to do is disable the IP address at one end of the link an re enable letting the OSPF reconnect and every thing then comes up again fine. I dont see any difference in what im doing there to whats happening when the link between the routers goes down.
OSPF shows it has the neighbor in its list while the MPLS has not re established.

I now have a support.rif from one of the routers. and some screen shots if MT are interested