Problem with left ALT key and Macros on fr_FR keyboard (right ALT works fine)

Platform: Windows 10
ISP: Proximus
Type of Internet Connection: VDSL2
Internet Connection Speed: 30Mbps/6Mbps
Date & Time: 2016-04-22 17:52 (GMT+1 Brussels time)
Frequency: Always (starting today/last patch, haven't played in a few days)
Character Name: Inzoum
Race: Tarutaru
World: Bahamut
Main Job: SMN
Support Job: RDM
Area and Coordinates: Anywhere (Baucedine Glacier at time of discovery)
Party or Solo: Any
NPC Name: N/A
Monster Name: N/A
Steps:
1. Play the game using a fr_FR keyboard (full size)
2. Press and hold the left ALT key to open up the "ALT" macro bar
4. Pressing keys number 1 or 0 correctly activate the corresponding macros, however pressing the keys numbered 2-9 do nothing at all

This only applies to the LEFT ALT key, and only in some combinations. The right ALT key works perfectly fine and activates any of the macros on the bar correctly. All macros on the CTRL bar are unaffected. There isn't anything wrong with the keyboard itself, as each of the keys function perfectly on their own, and also in combination in other software. I didn't have this problem until now, I could use either the left or right ALT keys with no difference. It doesn't matter which macro set is selected, or which bar number, the problem is the same all-round.

This is driving me nuts as I'm used to launching my macros using either CTRL or ALT with my left hand and hitting the numbers on the top row with my right hand...

Also important to note: On the fr_FR keyboard, the numbers on the upper row are accessed using the SHIFT key. The default characters for the keys on the upper row are: & é " ' ( - è _ ç à

This COULD have something to do with it...