Unable to use Waymarks while casting.

Im not sure if this is intentional or if its a bug. Regardless, you cannot set down Waymarks while casting. Making it really hard to organize mid-fight.

Time: X
Frequency: Always
World name: Leviathan
Character name: Kyng Ex
NPC name: X
Monster name: X
Class/Level: Arcanist / 50
Party or solo: Both
Race: Miqo'te Male
In-game time: X
Area and coordinates: X
Steps:
1. Begin casting.
2. Attempt to set a Waymark
3. ????
4. Cry.

Connection Specs
- Type of internet connection/provider: Century Link
- Connection Speed: 40 mbps down / 5 mbps up
- Modem maker/model number: X

PC Specs
-=-=-=-=- System Information -=-=-=-=-

CPU: AMD Athlon(tm) II X2 260 Processor 3.20 GHz
4.00 GB RAM
Windows 7 Ultimate
Gygabyte GA-870A-UD3 Motherboard
Onboard Sound
NVidia Gforce GTS 450
Some cheap generic keyboard
Razer Naga Mouse

-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

Browser Information
- Name and version of the browser currently in-use: Google Chrome 27.0.1453.116 m
- Internet Explorer Version: X

I have encountered this also. I think the problem stems from the fact that the Waypoints put you into 'Ground Targeting Mode' which is used for skills like Flaming Arrow and Shadow Flare, among others. So it's use is prevented while casting all spells to prevent a conflict of multiple ground targeting modes being used simultaneously. I don't know how the system works, but it sounds like a half decent theory at least. Anyone know if casters can initiate their Limit Break when in mid-spell cast?