Unable to save Bubble Chart gadget

Summary

Unable to save Bubble Chart gadget configuration.

Steps to Reproduce

1. Have a dashboard and add Bubble Chart gadget
2. Select any existing filter/project
3. Save

Expected Result

The configuration setting is saved and the gadget displays the data.

Actual Result

The gadget doesn't show the data and clicking Save does nothing. Refreshing the page, below error is shown:

Notes

Getting 400 error in Network Console:

PUT https://<instance URL>/rest/dashboards/1.0/10700/gadget/14200/prefs 400 (Bad Request)