Chrome added tab discarding last year. This is great for memory, but maybe not so great for sidewise. When Chrome discards a tab as described here: https://developers.google.com/web/updates/2015/09/tab-discarding?hl=en it loses it's connection to Sidewise. If the sidewise tab is hibernated and brought back, it actually opens a duplicate tab, leaving tabs open in Chrome that Sidewise cannot control.
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