autosnippet not triggering automatically

[hoshF]

Hello, sorry to bother you. I'm currently learning how to use LuaSnip, and I encountered a behavior that I don't fully understand.
What I want to achieve

I want to define a simple snippet like this:

s({ trig = ";a", snippetType = "autosnippet", wordTrig = false }, {
  t("\\alpha"),
})

I expected that once I type ;a, the snippet would automatically expand into \alpha without needing to press .
What actually happens

The snippet does not auto-expand.

Pressing <Tab> does not expand it — it just inserts a tab character.

Interestingly, if I remove snippetType = "autosnippet" and define it as a normal snippet, then pressing works fine.
My config (key points)

I did enable autosnippets:

return {
    "L3MON4D3/LuaSnip",
    version = "v2.*",
    build = "make install_jsregexp",
    event = "InsertEnter",
    config = function()
    vim.g.luasnip_store_selection_keys = "<Tab>"

        local luasnip = require("luasnip")
        luasnip.config.set_config({
            history = false,
            updateevents = "TextChanged,TextChangedI",
            enable_autosnippets = true,
            store_selection_keys = "<Tab>",
        })

        require("luasnip.loaders.from_lua").lazy_load({
            paths = { "~/.config/nvim/LuaSnip/" },
        })
    end,
}

My keymaps are standard:

vim.cmd[[
imap <silent><expr> <Tab> luasnip#expandable() ? '<Plug>luasnip-expand-snippet' : '<Tab>' 
imap <silent><expr> jk luasnip#jumpable(1) ? '<Plug>luasnip-jump-next' : 'jk'
smap <silent><expr> jk luasnip#jumpable(1) ? '<Plug>luasnip-jump-next' : 'jk'
imap <silent><expr> <C-b> luasnip#jumpable(-1) ? '<Plug>luasnip-jump-prev' : '<S-Tab>'
smap <silent><expr> <C-b> luasnip#jumpable(-1) ? '<Plug>luasnip-jump-prev' : '<S-Tab>'
  imap <silent><expr> <C-f> luasnip#choice_active() ? '<Plug>luasnip-next-choice' : '<C-f>'
  smap <silent><expr> <C-f> luasnip#choice_active() ? '<Plug>luasnip-next-choice' : '<C-f>'
]]
map('n', '<Leader>L', '<Cmd>lua require("luasnip.loaders.from_lua").load({paths = "~/.config/nvim/LuaSnip/"})<CR>')

I’m not sure if the issue is due to autosnippet behavior, my config, or interference from the completion engine.
Question

How can I trigger the snippet automatically?

Any guidance or clarification would be appreciated. Sorry if this is a basic question — I’ve read the docs but just want to confirm whether my understanding is correct.

Thanks a lot for LuaSnip — it’s an amazing tool!