XnView Software

using
XnViewMP: 1.3.1 - 64bit (portable)
OS: Windows 10 - 64bit

To reproduce:
- modify a picture in ViewMode (for example: resize or crop)
- trying to save the modified picture with Save As ... (with toolbar-icon / or menue-item File/Save As... / or hitting ESC -> "Save changed file"-dialog appears with button "Save As..." / or pressing Ctrl-Shift-S)
- it is not possible to save the modified picture under a different filename


Using the older version 1.3.0:
all above mentioned possibilities are working well

it works here, which output format do you use?

in
Settings/Formats/Saving
only JPEG/JFIF is selected.

Maybe my words "Save as ... doesn't work" are mistakable.
It's better to say:
the "Save As - dialog window" doesn't appear

Thanks to your detailed description I can reproduce the problem.

A workaround is to select more than 5 formats in Settings>Formats

thank you very much ...
Very cool workaround
Now it work's ...

This problem is supposed to be fixed in XnView MP 1.4.0. Please check and confirm the bug fix here.

tested in XnView MP 1.4.0 beta ...
The bug is fixed ... well done ... thanks ...