Times not converted when opening output of a previously ran simulation (outside script)

I got a message from @tessodk that this didn't work fully. This is a common workflow for large models:

First script: Create simulation, write it and dump it
Run model in commandline
Second script: Load simulation and call open_heads

Result: Data is loaded, but without any conversion to datetimes of the "time" coordinate. I think for some reason the reference time is not forwarded properly in this method.

See screenshots:

While these timesteps are included in the loaded simulation:

Deltares / imod-python

Times not converted when opening output of a previously ran simulation (outside script) #1036