Created attachment 106171 [details]
Demo

Hello.
It is a very old bug. It reproduces on different operating systems and KDE versions.
It impossible to run some kind of executable files from Dolphin.
GCC produces executable files with type equals to DYN (Shared object file).

$ readelf -h /usr/bin/konsole
ELF Header:
  Magic:   7f 45 4c 46 02 01 01 00 00 00 00 00 00 00 00 00 
  Class:                             ELF64
  Data:                              2's complement, little endian
  Version:                           1 (current)
  OS/ABI:                            UNIX - System V
  ABI Version:                       0
  Type:                              DYN (Shared object file)

So, when I'm double-clicking on that executable, I received the dialog with suggestion to select an application to open file with MIME-type equals to application/x-sharedlib.
I suggest you to ignore ELF type when the flag "executable" is present in the file attributes.