Sequences are being deleted randomly

Not if they're not present in any of your auto-saves. 

The behavior you've described is consistent with a user having manually (presumably, accidentally) deleted sequences; aside from that, we are aware of no behavior in PPro that would open, and then remove, sequences from a series of auto-saved projects.

As mentioned; if you become aware of a way to reproduce the behavior, we're interested in pursuing it further. 

I wish I could provide an example, except I would like to not go through the experience  of editing a 10min video for it to be taken away a random again.

Is there any other way I can salvage my previous edit?

If you can find a way to reliably reproduce the behavior, we'd be happy to pursue it further. 

I'm currently having the same issue, except I cannot even access my older edited versions within my sequence. All edits have been deleted/gone from every auto-saved version of my sequence. Although it still holds all of my footage and pictures. 

Agreed, hitting Cmd-S to save isn't the problem.

We are at a loss to explain how, other than through user action (deleting selected track items), some-but-not-all track items would be removed.

Does the thread to which Rach linked, resemble the experience you're having?

No, I don't have any special shortcuts and no external editign devices. There's no way I'm deleting 3/4 of a sequence by hitting command + S and then closing PR. It's happened multiple times. 

That suggests that user action, specifically inadvertent deletion, was what removed the track items. Do you have any custom keyboard shortcuts, that might contribute to track item deletion? Are you using any control surfaces, integrated with PPro? [They can send keystrokes.]

Rach's "similar to this?" question is also a good one.

No, auto saves were the first thing I checked.

Do your auto-save projects contain the trackItems, that went missing from your primary project's sequence?

Also, I ingested footage after the intial import and all that still appears in the bins along with in/out poonts from the clips. So everything is saving just the actual clips in the sequence are gone.