bug pad names overwritten when renaming pad matrix

Hello,
I am having trouble.
I have controller script with 8 pad matri
Each pad matrix contains 8 x 8 pads (emulating the Launchpad X custom modes).
I spent time to set a specific name for each pad > 8 x 8 x 8 = 512 pads to name.
Then I changed the name of the pad matrix and all the pad names are lost/overwritten ...!!
Is it a bug ?
Thank you for your answer.