How To Use The Workspace Function In Opera Browser??

[joko]

i had about 6 browser windows, each with about 15 tabs open, so i decided to finally make proper use of the workspace function on Opera browser.

I know the default workspaces 1 & 2 are basically just access to separate windows for whatever subject you like.

i figured those two are to split the area into two, say, personal & professional for instance.

So i created a load of new workspaces, named & assigned an icon. Subjects such as shopping, social media, finance, music etc.

& then i went through each open window & put all open tabs into the workspace they belonged in.

i figured when i wanted to look at various pages about health stuff, i just click the health icon & all the tabs i have saved about health would open in 1 browser window.
And the rest of the tabs would be in the relevant workspaces, so not using any resources.

however afterwards when i went to close some of the now empty open windows, it warned me i was closing lots of windows!

Then i noticed that when i clicked on the icons for the workspaces in the sidebar, it did nothing- at all - it didnt open all those tabs in that workspace.

the only way to open any tabs again, is to find the window it was originally in - which now looks like a brand new unused tab - & click on the icon & it opens the mix of tabs, just like it was before i did anything!

Have i done something wrong?
or not done something that i need to do?
or have i misunderstood what workspaces are for & what they can do?

If they dont do what i have said above - which i think is a reasonable expectation - i cant see any reason whatsoever for their existence.
may as well just 

any ideas?

Please no general links, ive already googled but i cant seem to find anything helpful & i dont want to wade through walls of text etc as im not very well

thanks :)