I fixed it in quasar.conf.js by setting the all option to auto, as below:
…
// Possible values for “all”:
// * ‘auto’ - Auto-import needed Quasar components & directives
// (slightly higher compile time; next to minimum bundle size; most convenient)
// * false - Manually specify what to import
// (fastest compile time; minimum bundle size; most tedious)
// * true - Import everything from Quasar
// (not treeshaking Quasar; biggest bundle size; convenient)
all: ‘auto’,
…