hello particle workbench user 
as you’ve no doubt learned, intellisense can be a bit finicky - it’ll flag non-issues in the “Problems” tab, report missing headers, etc. rest assured, if your code compiles you can ignore intellisense’s errors.
still, that’s not a UX we’re happy with so help us track down any lingering issues by reporting them here 
before posting, here are some trouble-shooting steps you can try to get things back in shape as well as instructions on what info to include in your report should your issue(s) persist:
- confirm you are working within a Particle project created via the
Particle: Create Projectcommand - close and re-open your project
- close and re-open VSCode
- check the version of the C/C++ extension (docs) - NOTE: if you are running an “insiders” build, rollback to a non-prerelease version (docs) and make sure to opt-out of the “insiders” channel in your user-level settings (docs)
- run the
C/C++: Reset Intellisense Databasecommand (ctrl/cmd+shift+p, then start typing the command name) - try adding
"C_Cpp.loggingLevel": "Debug"to your project’s./vscode/settings.jsonfile (or use VSCode’s UI - File > Preferences > Settings then search for “logging level”) - with logging level set to “Debug”, select the “C/C++” entry in the Output panel’s drop-down menu (top-right next to the panel’s “close” button), open your
.ino/.cpp, and share the log it produces. - with you your
.ino/.cppfile open, run theC/C++: Log Diagnosticscommand and share the output - run the
Particle: Audit Environmentcommand and share the non-sensitive parts - share the
C_Cppentries fromsettings.jsonin your project and user settings - verify that your project
settings.jsonincludes"C_Cpp.default.configurationProvider": "particle.particle-vscode-core" - create a minimal
.inoor.cppfile that reproduces your error (or if you are comfortable sharing, a link to a.zipfile of your entire project)
after each step, verify that you are still seeing inaccurate issues in the “Problems” tab within VSCode.
see here for instructions on how to open your settings.json files:
once again, thanks for trying Workbench 
