LSP suggestions don't appear in certain files, although LS loaded

[ajur58]

Steps to reproduce:

• Open .html file -> tailwindcss autocomplete suggestions work
• Open .heex file (elixir template) -> tailwindcss autocomplete suggestions don't work
• Repo with nvim lsp config: https://github.com/ajur58/config-nvim/blob/main/after/plugin/lsp.lua

In both cases :LspInfo shows that the correct clients are attached to the buffer. Tried with both vsnip and luasnip.
I'm opening the ticket here as this is my best guess, not sure how to debug further.

Help is much appreciated!