Dyalog 20.0 does not bring in the StartupSession specified by DYALOGSTARTUPSE

20.0.54382 64-bit Unicode on MS Windows

in cmd.exe
unzip the latest qSE for 20.0 to c:\tmp\
while the 20.0 install directory just has the installed StartupSession last changed in StartupSession\Dyalog\util.apln has 1.57 at the top.

cd "c:\Program Files\Dyalog\dyalog*20.0*unicode"
dyalog.exe DYALOGSTARTUP=c:\tmp\qSE-20.0\StartupSession.aplf DYALOGSTARTUPSE=c:\tmp\qSE-20.0\StartupSession

⍝Test by looking at the version number at the top
)ed ⎕se.Dyalog.Utils

Similar settings using qSE for 19.0 work with 19.0, but not 20.0. I can get 20.0 to work with an undocumented parameter instead of DYALOGSTARTUPSE.

Real world user story: I want to use the latest qSE, but I cannot modify the 20.0 install directory in C:\Program Files\ until the next scheduled 20.0 update rollout which might be a long time away.

Start with the StartupSession.aplf and StartupSession paths in the qSE-20.0 archive, then reproduce the command-line setup on Windows using DYALOGSTARTUP and DYALOGSTARTUPSE. Compare the same settings with 19.0 and investigate why 20.0 does not load the external StartupSession. Done means the latest qSE StartupSession loads on 20.0 without changing the installed Program Files directory.

Written by the indexing model from the issue text.