In VSCode Tauri app RA builds dependencies but doesn't provide intellisense

[happybeing]

rust-analyzer version: (eg. output of "rust-analyzer: Show RA Version" command, accessible in VSCode via Ctrl/⌘+Shift+P)
Version 0.3.2593, Server Version 0.3.2593-standalone

rustc version: (eg. output of rustc -V)
rustc 1.88.0 (6b00bc388 2025-06-23)

editor or extension: (eg. VSCode, Vim, Emacs, etc. For VSCode users, specify your extension version; for users of other editors, provide the distribution if applicable)
VSCode
Version: 1.104.1
Commit: 0f0d87fa9e96c856c5212fc86db137ac0d783365
Date: 2025-09-17T23:36:24.973Z
Electron: 37.3.1
ElectronBuildId: 12404162
Chromium: 138.0.7204.235
Node.js: 22.18.0
V8: 13.8.258.31-electron.0
OS: Linux x64 6.14.0-29-generic snap

relevant settings: (eg. client settings, or environment variables like CARGO, RUSTC, RUSTUP_HOME or CARGO_HOME)

repository link (if public, optional): (eg. rust-analyzer)

code snippet to reproduce:

// add your code here

I've been using VCCode and RA successfully without issue for years and today I find that some things are no longer working as expected. I'm not certain this is due to a change in RA but the symptoms are strange so posting here for assistance in tracking this down.

Firstly, if I open a workspace in one of my regular Rust projects all is fine.

When I open a Tauri project, which doesn't have Cargo.toml in the root, but in ./src-tauri I see Rust Analyzer rebuilds dependencies showing that it has found ./src-tauri/Cargo.toml but the intellisense features no longer work. This was fine last time I was using VSCode, and has worked without any messing about for years.

I'm using Ubuntu 24LTS and did recently have an issue and have reverted to booting the previous kernel, so perhaps this has impacted VSCode+RA. I do see the font I get in VSCode has changed, but everything else seems fine so not sure this is relevant, or if something has changed in RA, or just something has become corrupted.

I tried uninstalling and re-installing RA.

A web search suggested I need a Cargo.toml in the root, but I've not needed that before.

I also note that in a workspace where the root folder contains multiple subfolders, each with different projects in it, RA now gives an error (whereas this worked fine in the past):

2025-10-05T15:43:35.551665583+01:00 ERROR failed to find any projects in [AbsPathBuf("/home/user/src/autonomi-apps")]
2025-10-05T15:43:35.576452916+01:00 ERROR FetchWorkspaceError: rust-analyzer failed to fetch workspace
2025-10-05T15:43:35.676630973+01:00 ERROR FetchWorkspaceError: rust-analyzer failed to fetch workspace

I found a (StackExchange issue](https://stackoverflow.com/a/77771661) from 2022 which says the Cargo.toml unless you explicitly link the subprojects using "rust-analyzer.linkedProjects" but assume that is no longer the case as I've never needed to do that.

The odd part is that it does seem to find the Cargo.toml and build the dependencies. It's just the intellisense (hover of type, and right-click "Goto Definition" etc) features no longer work.