Snapshots Inaccessible

[talismanick]

I persist all my tabs (because Auto Tab Discard means I only use a few Gb of memory at any given moment, for recently-used tabs), and categorize them with Sidebery. I'd estimate I've accumulated ~800, because they accrete across restarts with "remember history" and "startup > open previous tabs and windows"

My browser crashed, so, per the usual, I restarted. This time, however, it loads a window with a blank tab (known to happen) and crashes on restoring from "History > Recently Closed Windows" (new). The window freezes, then disappears, when I'd normally have both the dummy empty-tab window and the window with all my tabs.

Sidebery used to consistently snapshot automatically (I checked a few weeks ago), but now it's refusing to help recover the most recent snapshot:

The main menu says there's still 126MB of data under "snapshots_v4". Is there any way I could access this and recover my tabs?

Apologies if this has been submitted before: I didn't see anything like it among the 100+ issues mentioning "snapshots". (the ones I opened and read completely, at any rate)