FortiSwitch 124F-FPOE Private VLAN Support?

We installed two FortiSwitchs in stand alone mode at a new small facility last year. A 448E-POE in main network closet connected to Metro-E and a 124F-FPOE in a network cabinet to link the back to closet with Fiber. Recently we added a FortiGate 60F to manage some planed IoT devices. After reviewing network settings we though the best method to move forward was to utilize Private VLANs to isolate the IoT devices in a single subnet behind the FortiGate. We tested on the 448E-POE switch and then discovered that the 124F-FPOE doesn't support them.

Does anyone know if I convert the 124F-FPOE to be managed by the FortiGate, if it will then be able to support Private VLANs?

Trying to decide if I need to replace it, or convert it to managed without doing it first since its in a manufacturing facility with the only extended  downtime window from 1-4am on Sundays. I really don't want to come in to do the migration if its not going to work only to have to come back in a few weeks later to swap switch out.