- be this from the layer palette or dragging layer onto '+'
...to be clear it *sometimes* works,. and other times not ? ...no idea why ... ?
any thoughts ?
Can you say us which OS and which Illustrator version do you use?
Do you have a screenshot (or better: an example file) for us.
I cannot replicate such a behaviour with my own files.
- think I've sussed it... ...my layer 'names' were waaaaaaay too long (!)
(I have some erm 'working memory' issues, so as and when I remember I 'track' what step-by-step changes I'm doing in/as abbreviations in layer name hence they often get loooooong! - erm, kinda embarrassing to admit to...)
There is no reason to find anything embarrassing.
I have also worked with extremely "long" layer names. But I never noticed that it was no longer possible to duplicate them.
How many characters do the names of your layers have?
Also avoid using special characters in your layer names that interfere with Unix, such as colons, Percentage and slashes. Msot others are ok are ok to use, adn Parenthesis and underscores are popular.
Not sure about some of these foreign characters, but never had a probelm when I get files using for example a chinese language.