Incompatible with Elytra Slot?

[HatTrkPatrk]

Running the highest common version between Polymer, Polymer-Trinkets and the Elytra Slot mod found at https://modrinth.com/mod/elytra-slot/version/6uCj1VmZ
which is 1.20

Server 1.20, mods list (note: the elytra slot jar's filename says 1.20.1 but is listed on modrinth for both 1.20 and 1.20.1)

Connected to the server with 1.20 vanilla client works fine;
I can right-click the Chest armor slot to open the trinkets UI, or I can type /trinkets
I can place the elytra into the slot
But I cannot fly/glide as if the elytra were equipped

Is this a known incompatibility/is there a workaround?

Thank you

[Patbox]

Likely it requires client side code to work, which would require specific compatibility