Closed tabs still showing as open in Sidebar

Yes. And I think that it is hopeless. The developer doesn't even reply any more in this forum. I have dropped this extension, using now GraphiTabs. It is a very different kind of management, but waiting for a better extension really comparable to TreeStyleTab (which is only for Firefox), I have preferred to drop Sidewise. There is also Tabs Outliner... but it is the same mess as in Sidewise. So for the moment for me it is GraphiTabs... which doesn't make many things but which makes them extremely well.

Thank you for your response!

As we can here here (by hovering the mouse pointer on the mention "1 year ago") the most recent reply from the developer was on the 26 February 2017. For the last 5 years he replied only 4 times !

So it appears clearly that this extension can be considered as an abandonware. Probably that the developer would like to work on it but for a reason or another he can't. Disinterest ? Procrastination ? Too many things to rework from scratch ? Lack of time due to the family responsibilities or the professional work ? (which are priority of course, it is human)

Many legitimate reasons are possible (even the procrastination I consider it as legitimate because it is a kind of disease, very different from the laziness). Whatever the reason, it is now obvious that there will never be any revolution in the resolution of all the very complex bugs that we all have observed and which are obviously related to the deep structure itself of the application and would mean a rewrite from scratch of more than 50% of the code. That's why I write that it is hopeless. Development of applications was a part of my job before my retirement, but unfortunately it was in biology so not at all in that kind of applications. And I feel now too old and too weak to manage to cope, otherwise I would have accepted to take the work over.

The only solution that I can see is to definitely open the source code to the community so that someone else may take it over. As soon as the source becomes open it is certain that I will regain hopes, but as long as it remains in the current state it is obvious that we can't expect any revolution in the life of this project.

Cheers!

Jacques

Have you tried "emergency restore" in the advanced options?