Part names are set to "Synthesizer"

Starting MS version 4.0, any score I publish to musescore.com shows part names as "Synthesizer", which is not how wrote or intended to score to be displayed. I mainly work in vocal music. This is not an issue in version 3.x. In v. 4, the part names show correctly, but on musescore.com, they show as "Synthesizer". Is this a bug?
See example:
https://musescore.com/user/32822595/scores/9498301?share=copy_link
My work around: All of my recent works done in v. 4 were imported into v. 3 to correctly upload to musescore.com.