Is this a known bug? I just upgraded to cutting edge hoping that would resolve the issue but it hasn’t. It crashes when values are copied from an existing rmx scaled glyph or from a text file. It was working previously, only other thing I can think of is that the number of masters in this file grew to four from two and contracted back down to two. Just an idea as I know master numbers has been an issue in the past.
I installed the latest RMX plugin.
osx 10.10.5 glyphs 2.6.4 (1273)
Thanks for the report. No, it is not a known bug. Could you send the .glyphs file that causes the crash? If I can reproduce it here I am sure the bug will be quick to fix.
Thanks Tim — just messaged you with the file.
Btw, which version of RMX are you using? Is it the latest version? You can do Preferences > Addons > select Font Remix Tools > click on Check for updates.
I’m not sure of the previous version but I updated to latest rmx in the hope that would resolve it.
Currently the update check crashes Glyph 
You mean, Glyphs crashes when you push the button “Check for updates”? That would be a case for @GeorgSeifert. The data returned by my server as you push that button is rather primitive (and hasn’t structurally changed recently).
Probably the reason for the crash is that you are using OS X 10.10 Yosemite whereas the latest version of RMX is built for OS X 10.11 or later. Sorry, looks like I underestimated that some people are using very old OS versions. Any particular reason why you are not upgrading?
If you contact me by email I can send you a version built for OS X 10.10.
Ha… I’ve heard that before. It’s not that old. Frankly I distrust upgrades as a general rule 
The thing is copy/paste works for other fonts with this version of rmx, but any way…
Will drop you a mail.