Sidewise not opening anymore, rebooted, emergency restored, nothing.

I'm a paid user of Sidewise and about 3 weeks ago, it simply stopped functioning. I haven't added any more extensions, just using it normally like I do every day.

I have disabled it, rebooted, run disk utility and first aid, just about everything I can except totally remove the extension, because it would abandon all my hibernated tabs.

Anyone got any suggestions?

Thanks,

Ross