Hi Mathias,
with MC 15.5 b3094 x64, Win11 24H2 b26100.4061 x64, this is what I am finding : -
@var $options[] = {“RECYCLE”, "NODIALOG"};
DeleteFiles($array, $options);
- deletes files (not recycle bin) No dialog but progress briefly appears as expected
@var $options[] = {“RECYLE”, "NODIALOG"};
DeleteFiles($array, $options);
- deletes files (not recycle bin) No dialog but progress briefly appears as expected
@var $options[] = {“RECYLE”};
DeleteFiles($array, $options);
- deletes files to recycle bin with dialog
@var $options[] = {“RECYCLE”};
DeleteFiles($array, $options);
- deletes files (not to recycle bin) with dialog
Perhaps you can replicate this? 
There are some issues with your code
If you copy paste your code.. You see if you run it from the debugger that
@var $options[] = {“RECYCLE”, "NODIALOG"};
results in an array with 1 items instead of 2..
But when I retype it. I get 2 items, I then replaced the " from you code with my ". and it works.
So you use some none standard " character that mess it up