What about this one:

ClassMethod Indirection() [ ProcedureBlock = 0 ]
{
 N (evenTotal)
 set TABLES(0)="EVEN" 
 set TABLES(1)="ODD"
 
 for i=1:1:100 {
   set table = TABLES((i#2)) 
   set @(table_"("_i_")")=i
   
   // Xecute alternative, same issue 
   ; set cmd = "set "_table_"("_i_")="_i 
   ; x cmd 
 }  set evenTotal=0
 set i="" for { set i=$ORDER(EVEN(i)) QUIT:i=""  
   set evenTotal = evenTotal+EVEN(i) 
 } 
 zwrite evenTotal
}

It is Windows 64 bit. But the problem is solved now.

Thank you @Ohata Yuji You seem to be right. In the meantime, I managed to start Language Server as follows:

VScode runs smoothly on my second computer, so I looked for differences. I have Caché installed on the second computer, Iris on the troubled one. The problem disappeared when I installed Caché on the troubled one.