There's a bug with the Redeemed Citadel store when trying to claim the 5 weekly mount tokens.
I didn't claim anything yet for the entire week.
Yesterday, Milestone III was completed and this brought the possibility to claim mount tokens every week.
However, if you claim companion tokens first, mount tokens are disabled for purchase and you get the message "you have already purchased this item this week".
Viperion Nexus - cleric healer.
Viperion Helsing - warlock DPS/healer.
Viperion Justifer - paladin tank.