Alternates not showing in preview

Hi, I have just had my first font approved and released on
The font has a .dlig and multiple .ss01 characters.
Exported at .OTF and .TTF these work fine in desktop apps, as Stylistic Set> Set 1 in In Design for example, but in the live preview on they don’t work, even though the dropdown recognizes that they exist for selection.
I asked the myfonts team and they said there was nothing wrong with the actual fonts. I know this may seem like a question for myfonts, but I was wondering if anyone had had experience with problems with their alternate sets?
Many thanks

Have you tested the fonts in a browser outside of the Myfonts system?

Thanks for the response James.
I supplied myfonts with OTF and TTF and they made the webfonts so I don’t actually have those files.
I have my own webfonts I exported from glyphs 2 in my website preview, exported as both TT and OT to see if it made a difference and I don’t get alternates or ligature in Chrome. In Firefox I seem to get the alternate alphabet but not alternate numerals… and no ligature.

I wonder if there is a conflict between the .dlig and .ss01 extensions? Fonts that I have previously made with just a .dlig, the ligature works automatically in my browser.

It seems strange that the fonts work perfectly in desktop packages, and myfonts said there was nothing wrong with how they were made. So is it an issue with the web export?

Thanks again

The only way to tell is to take the webfonts and see if the features work.