Noticed the same problem here. Linux server running Xtigervnc, and 2.8.63 on Windows connects and works fine while 2.8.75 only shows a blank screen.
Commenting here so all the lost souls see it: This plugin has not received an update since 2013, so we can safely assume that development on it is very much dead. (Oh noes! But fear not!) Direct your attention towards this fork instead: https://github.com/victor-rds/KeeTrayTOTP