F5 Data Group List in iRule

I recreated this issue in the WebUI on a VE running 11.5.4. Specifying the IPv6 mask as "/64" resulted in the "Invalid mask" response. When I input the mask as "ffff:ffff:ffff:ffff::" it was accepted without error.

Interestingly, the mask "/64" is accepted when configuring via tmsh:

(tmos) create ltm data-group internal my_ipv6_datagroup type ip records add { 2001:1:2:3::/64 } (tmos) list ltm data-group ltm data-group internal my_ipv6_datagroup { records { 2001:1:2:3::/64 { } } type ip }