Some years ago there was a tempory restriction to use OPN CLB above FL300 due to a glitch in one of the FMGC updates which caused to engines to go to idle at level off if the ROC at level off was less than 300ft/min. Happened to me twice. However that glitch was corrected years ago and I doubt there would be any aircraft still with that FMGC standard.
Have a nice day