This sounds faintly familiar to me too. I maybe had that really long time ago (2 years), can't remember anything. However, at present I would suspect it is a LOD error. So maybe delete your DistantLOD folder and let Tes4Lodgen generate it all new. However I have a very low confidence in my suspiscion because pink is missing meshes, right?
I've run Tes4LodGen just before this happened - but I'll try to delete the folder and redo it.
As to your save issue with SLSS.... it's most bizarre. If you tried out Kuertee Autosave and Time for testing, you could possibly establish if the defect is actually with SLSS. For that matter: Have you tried to disable / uninstall SL completely, play some, and re-install SL? Maybe something is wrong or "happened" with the SL files? Essentially I'm clueless.
Haven't tried standalone autosavers - sounds like a good idea. I've made a clean save w/o Streamline and rechecked/reinitialized it (and deleted all streamsaves as well), but I haven't uninstalled/reinstalled. Yes, it's completely odd - can't see why a streamsave would be any different from a hard save in the first place.
Why do you put SL at the very end? Boss puts it somewhere in the middle, I have it there, it's ok there (2 months of playing for me there). Same with FormID Finder.
I've always had them there and had no issues with it. They were placed last by BOSS earlier on. As I understand it load order should be rather unimportant for them so BOSS placement is more or less arbitrary, but I guess there are a couple of exceptions to that which is why they were moved. Anyway, I'll try placing them as BOSS does currently and see if it helps.
And:
68 Cobl Tweaks - FCOM.esp [Version 1.72]
Where did you get that from? I looked in my Cobl download archive, it's not there, nor in FCOM Convergence?
Beta-testing the upcoming release. Or I should rather - the little time I have for playing seems to go into trouble shooting odd issues right now...