Read the instructions after trying several browsers to sell clubs....
You need to un-equip all clubs in all 4 sets of the bag saving the set completely before moving to the next set in the same bag ...
Do this for all 4 sets in the bag .. god help you if you have more than 1 bag ...
With all 4 sets completely empty of the clubs you want to sell.
drag the bag out of your inventory.
Save changes one last time ( 20 minutes later .... )
Go and sell the club the usual way ...
Surely with the amount of money we spend to play this game, you would have this type of *** fixed my now ...
Its not a bug ....
Its a strategic way to piss people off so they just keep spending money out of frustration ...
Anyways, back to pulling out my hair when loosing a $3.50 ball when the winds do the exact opposite of what they tell you when approaching a green around water ....
Good luck and I hope the above helps.
Cheers