Miles,
I have access to an early version SSA3021X, ( Hardware ver 07.03.00 produced in 2017 ), with FW 1.2.9.3a.
This unit behaves exactly as described in the Siglent RBSSA3X25 Reflection Bridge Manual.
Unfortunately I can not install and test the firmware ver that you are using as it is not compatible with this early HW ver.
This may not be relevant, but I have noticed that in the latest version of the user manual for the SSA3000X, ( UM0703X-E03B ), all reference to the "Reflection Measure Mode", that were in the previous ver of the User Manual, ( UM0703X-E02B ), have been removed.
As far as I am aware , the Factory Reset will only return the instrument to some pre-defined settings and will not change the trial times for the options. At least it never has for me on Siglent or on other brands of equipment.
Hopefully Tautech will be able to find an solution for you.
Regards.