Match Frame does not work properly or allow me to make In and Out markers in Source Window

Figured it out. I don't understand how Productions keeps all of its constituent Projects talking to each other, but there seems to be a continuous break. I was confused because

1) I could not match frame any more, nor turn Proxies off. This lead me to believe media had been unlinked again somehow

however

2) everywhere I looked, my media was connected. In the timeline of my multicams – online, in the project panels of my media projects – online. Link Media was greyed out because everything was connected. I could Reveal in Finder and everything was connected. I even forced the media online, and then reconnected it. None of that worked.

3) Reassociate Source Clips was greyed out as an option. (side note – how do you reassociate multicam clips anyway?)

4) I went into one of my edit timelines, selected all, copied and pasted in a new dummy project – things worked fine: I could turn proxies on and off, and I could match frame and set In and Out points.

So the issue was entirely with my Edits project – the one with my actual editing timelines. So I go in the timeline, Select All, right click and want to select Link Media – but everything is connected there. I was at a total loss.

It was only after about a half hour of freaking out that I decided to right click my sequence in the project panel. There and only there was the Link Media option clickable – so I clicked it and everything was offline. 

I don't know why this happened, and I don't know why it happened only to this timeline, or why this seems to be a repeat issue that manifests in slightly different ways, or why having everything seemingly linked doesn't actually mean things are linked, or what arcane method Productions uses to communicate with its constituent parts, but it shouldn't be this complicated. No warnings, no errors, files communicating with metadata properly except for via one off-hand route – it's a mess, and it keeps me from editing. 

So if anyone else comes across this behavior in Premiere  –

1) try relinking the media in your timeline by selecting all, right clicking and selecting Link Media

if that doesn't work

2) Try going inside your multicam clips and right clicking and selecting Link Media

if that doesn't work

3) Go into wherever Project your source files live and in the Project panel select your media, right click and select Link Media

and if that doesn't work

4) Go back and select whatever sequence is giving you an issue in the Project panel of the project in which it lives and right click and Link Media that way

At different times different methods solved the problem, and only that method. 

We'll see what happens next. Next thing I learn I'll have to Link Media by running a tin can on a string from Adobe HQ to my office and saying the magic word.