How to regain lost 'storage folders' ?

My email account is GMail. I used to have Windows Essentials 2012 for my email client - when that no longer worked, I changed to EmClient. The latter kept all the folders I had created in Essentials over the years; to my surprise I found those same folders in Gmail; recently some unknown even caused EmClient to stop displaying the numerous 'storage folders', and so did Gmail; I thought I had lost them, but after some time (a day ?) the storage folders re-appeared in EmClient, however, they are still missing from Gmail. I wonder if there is a way of restoring them to Gmail ?

Windows / Chrome 105.0.0.0