Cannot run entire cell in .qmd file

This issue has arised in cursor and come about suddenly, when it was working when I first installed the quarto extension.

When I try to run an entire cell in this .qmd file:

a = 1
b = 2

c = a + b
print(c)

I am unable to run the whole code chunk in any way. I tried keyboard shortcut (cmd + shift+ enter) and to press the run cell button. In both cases, the line my cursor is currently on runs and the cursor moves to the next line. if the cursor is outside of a code chunk, the output is "Error: attempt to use zero-length variable name" and, again, the cursor moves to the next line. In the example above, I can't assign values to a and b simultaneously, or generate then print c at the same time.

Why is this happening? The keyboard shortcuts are all standard; quarto.runCurrentCell is cmd + shift + enter. My settings in cursor are as follows:

{
    "workbench.startupEditor": "none",
    "diffEditor.ignoreTrimWhitespace": false,
    "redhat.telemetry.enabled": false,
    "editor.unicodeHighlight.ambiguousCharacters": false,
    "remote.autoForwardPortsSource": "hybrid",
    "files.associations": {
        "*.rmd": "rmarkdown",
        "*.qmd": "quarto",
        "*.Rmd": "rmarkdown"
    },
    "workbench.settings.applyToAllProfiles": [
        "r.linting.enable"
    ],
    "workbench.colorTheme": "Default Dark Modern",
    "extensions.ignoreRecommendations": false,
    "[r]": {
        "editor.defaultFormatter": "REditorSupport.r",
        "editor.formatOnSave": true
    },
    "editor.largeFileOptimizations": true,
    "r.plot.useHttpgd": true,
    "r.plot.width": 800,
    "r.plot.height": 600,
    "r.lsp.enabled": true,
    "r.rterm.mac": "/usr/local/bin/R",
    "[rmd]": {
        "editor.wordWrap": "on",
        "editor.formatOnSave": false,
        "editor.defaultFormatter": "REditorSupport.r"
    },
    "r.linting.enable": true,
    "r.linting.lintr.linters": "linters_with_defaults(line_length_linter(120))",
    "git.enableSmartCommit": true,
    "git.autofetch": true,
    "git.confirmSync": false,
    "files.autoSave": "afterDelay",
    "files.autoSaveDelay": 1000,
    "terminal.integrated.defaultProfile.osx": "zsh",
    "editor.folding": true,
    "editor.foldingStrategy": "auto",
    "workbench.editor.enablePreview": false
}

It has made working with quarto really frustrating in cursor (and by extension, VScode).

Reproduce the problem in a .qmd file with the two R chunks shown, using Cursor or VS Code and quarto.runCurrentCell. Start by tracing how the run-cell command identifies the current chunk and handles the cursor outside a chunk; done means the entire chunk runs and the outside-chunk case no longer sends an empty line.