Treeview plugin - nodes don't always expand


Seeing an issue with the treeview plugin where nodes don’t always expand. Whenever it happens I’m seeing the following in the console:

Uncaught TypeError: Cannot read property ‘metaData’ of null
at F.u [as getMeta] (ext-all.js:22)
at F.readRecords (ext-all.js:22)
at (ext-all.js:22)
at F.processResponse (ext-all.js:22)
at F. (ext-all.js:22)
at Object.callback (ext-all.js:22)
at F.onComplete (ext-all.js:22)
at F.onStateChange (ext-all.js:22)
at XMLHttpRequest. (ext-all.js:22)

Any ideas what could be causing the issue?