I find that sometimes the game will not allow me name a particular item I am enchanting. And when this happens I often have to unplug my computer to exit enchanting.
Lets say I have a dwarven bow I want to enchant...sometimes the game will let me name it; and sometimes not.
If not...if I use the console to spawn another bow, it might, or might not, let me name that bow.
So the glitch seems to be related to specific items and not item types...I have named other dwarven bows.
Also...I use categorised favorites...and some items dont get picked up by it...so if I favorite them they dont show up on the favorites menu.

Any ideas?

Your on a PC, right? And using the console command? I read somewhere, and I can't remember where, that naming is buggy if you use the mouse during the process. The solution I read was to use only the keyboard arrows and enter keys during the whole enchanging process if you want to rename.

Yes I have been using the mouse...my M3 is mapped for use as favorite key...and that's the key used to initiate naming. That could be it. But it's intermittent; sometimes it works. Thanks.

I 'found' the weapon that was missing from the 'categorised favorites menu'...it is listed under spells...!

For anyone who has had similar anomalies.
I figure out why some of my named items were listed in the wrong lists...for example an enchanted bow being listed under spells.
It has to do with the keywords used to categorise items. I had used the word 'flames' in the name of the bow; that word is identified as related to the 'flames spell' so the item gets listed under spells. So I enchanted a bow using the keyword given in the enchanting effects list...'fire' in this case...and the 'Bow of Fire' is correctly listed under weapons.