Can't create APM policy with modern customization

I cannot create a APM per-session policy with Customization set to Modern (default). It fails with the following error message:

01070712:3: Values (/Common/modern) specified for Customization Group (/Common/webtop-ap_general_ui): foreign key index (customization_sourceFk) do not point at an item that exists in the database.

This happens on all my BIGIP VEs. If I create it with Standard customization it works. I just fired up a brand new BIGIP VE, provisioned LTM and APM and tried it and got the exact same result.

The LTM and APM log does not say much (and say the exact same thing):

# tail /var/log/ltm
Mar 3 03:22:37 bigip4.example.com warning mcpd[6827]: 01071859:4: Warning generated : apm log-setting (/Common/default-log-setting) is attached to apm profile access (/Common/webtop-ap). You may replace this log setting with your own setting.
Mar 3 03:22:37 bigip4.example.com err mcpd[6827]: 01070712:3: Caught configuration exception (0), Values (/Common/modern) specified for Customization Group (/Common/webtop-ap_general_ui): foreign key index (customization_sourceFk) do not point at an item that exists in the database..


# tail /var/log/apm
Mar  3 03:22:37 bigip4.example.com warning mcpd[6827]: 01071859:4: Warning generated : apm log-setting (/Common/default-log-setting) is attached to apm profile access (/Common/webtop-ap). You may replace this log setting with your own setting.
Mar  3 03:22:37 bigip4.example.com err mcpd[6827]: 01070712:3: Caught configuration exception (0), Values (/Common/modern) specified for Customization Group (/Common/webtop-ap_general_ui): foreign key index (customization_sourceFk) do not point at an item that exists in the database..

Troubeshooting process:

• Saved and reloaded config
• Rebooted device
• Tested on multiple BIGIP VE, all running 15.1.0.1
• Fresh install on new VE with minimal config

I found nothing when googling this. Any ideas?