NeoVim LSP (Mason, LSP Config) - No features working

[soer9459]

I have installed Marksman with Mason, and set it up with LSP config.
My config works for all other LSP servers, but marksman does not work at all. No autocompletion, linking etc.
The LSP does attach to the buffer, but nothing works.

CmpStatus shows that it is available as a source:

Can anybody tell what is going on?
The LspLog output the following messages when opening a markdown file:
[START][2024-02-01 04:25:48] LSP logging initiated
[ERROR][2024-02-01 04:25:48] .../vim/lsp/rpc.lua:734 | "rpc" | "/Users/[username]/.local/share/nvim/mason/bin/marksman" | "stderr" | "[04:25:48 INF] <LSP Entry> Starting Marksman LSP server: {}\n"

This is my LSP config (I'm using nvim-cmp for completion):

return {
    'williamboman/mason.nvim',
    dependencies = {
        'williamboman/mason-lspconfig.nvim',
        'neovim/nvim-lspconfig',
        'hrsh7th/cmp-nvim-lsp',
    },
    config = function()
        require('mason').setup { }
        require('mason-lspconfig').setup {
            ensure_installed = { 'bashls', 'lua_ls', 'texlab', 'pyright', 'taplo', 'marksman' },
            automatic_installation = true
        }
        require('mason-lspconfig').setup_handlers {
            function(server)
                require('lspconfig')[server].setup{
                    capabilities = require('cmp_nvim_lsp').default_capabilities(),
                }
            end
        }
    end
}

and my nvim-cmp config:

return {
	'hrsh7th/nvim-cmp',
	dependencies = {
		'hrsh7th/cmp-buffer',
		'hrsh7th/cmp-path',
		'hrsh7th/cmp-cmdline',
		'hrsh7th/cmp-nvim-lua',
		--'hrsh7th/cmp-nvim-lsp-signature-help',
		'L3MON4D3/LuaSnip',
		'saadparwaiz1/cmp_luasnip',
		'hrsh7th/cmp-nvim-lsp',
	},
	config = function()
		local cmp = require('cmp')
		cmp.setup {
			snippet = {
				expand = function(args)
					require('luasnip').lsp_expand(args.body)
				end
			},
			mapping = cmp.mapping.preset.insert {
				['<C-k>'] = cmp.mapping.confirm({ select = true }),
				['<C-d>'] = cmp.mapping.scroll_docs(-4),
				['<C-f>'] = cmp.mapping.scroll_docs(4),
			},
			sources = {
				{ name = 'luasnip' },
				{ name = 'nvim_lsp' },
				{ name = 'nvim_lua' },
				{ name = 'buffer', keyword_length = 3 },
				{ name = 'path' },
			},
			formatting = {
				format = function(entry, vim_item)
					local abbrev = {
						buffer = "buf",
						nvim_lsp = "LSP",
						nvim_lua = "nvim",
						path = "path",
						luasnip = "snip",
						cmdline = "cmd"
					}
					local source = entry.source.name
					vim_item.menu = "[" .. abbrev[source] .. "]"
					return vim_item
				end
			}
		}
		cmp.setup.cmdline(':', {
			mapping = cmp.mapping.preset.cmdline(),
			sources = {
				{ name = 'path' },
				{ name = 'cmdline' },
			}
		})
		cmp.setup.cmdline('/', {
			mapping = cmp.mapping.preset.cmdline(),
			sources = {
				{ name = 'buffer' },
			}
		})
		vim.api.nvim_set_keymap('i', '<c-h>', '<cmd>lua vim.lsp.buf.signature_help()<cr>', { noremap = true, silent = true }) -- Do keymapping differently maybe?
	end
}