Hi. I have the same problem. I can’t translate my About content.
I also had the problem with being unable to translate widget content (Features, Services, etc). This has been resolved by hacking the wpml-config.xml file.
See my (resolved) support thread on WPML forum here: https://wpml.org/forums/topic/admin-texts-are-randomly-not-translated/
Please provide a fix for translating About content.