1 material (electric_socket_type_j.sbsar, substance source) not loading in substance painter library

Every material I download I put in an own library and can load it without a problem in substance painter later on, except this one: electric_socket_type_j.sbsar. I downloaded it in April 2022, and have done so again today (both files 190 kb).

I deleted the thing several times, closed painter several times, restarted the computer and so on.

I also tried it with the standard "Your assets" library.

I opened the sbs in substance designer and sent it to substance painter.

I "published" the material and put that in these libraries.

I tried all this with different, shorter names.

Everything to no avail. It's just not under materials. It's also not in the .alg_meta folder (every other material is also there).

If I install another material into the same folder, it works perfectly swell.

As I use substance only for a short time, I'm far from knowing enough (but cudos to the designers: one can be productive from day 1). The thing may be shown somewhere else than in the materials library or just not working properly (this is why I exported it anew from the sbs).

In designer the material looks ok, nothing wrong with it. It can be adapted, changed, etc.

How can I get the thing into painter / respectively what is the reason it doesn't? Or is it accessible elsewhere than in materials (I believe I looked everywhere, tried the search etc. It's not shown in the library).

Thanks very much in advance.