Which version of FF do you use?

* Reply to @nauticelrebor:
I managed to reproduce the issue on windows 10. I am investigating and fixing it ASAP. Thanks!
* Reply to @nauticelrebor #2:
It seems that this error disappeared. I can not reproduce it anymore. Probably it was an error in FF.
Or as I guess the Textnotes was not downloaded properly from the Mozilla server.
If you still have this issue could you contact me to my support e-mail. Thanks.