When server is expanding macros in a string and detects an unsupported (by location) macro, it increments cursor position in the string and tries to find a token again. This will lead the same token being parsed and 'refused' again and again until the cursor position will reach the token.

Instead of incrementing cursor position by 1 it should be set to the left position of the unsupported token +1. The following patch should fix it, but needs to be carefully evaluated.

Index: src/libs/zbxserver/expression.c
===================================================================
--- src/libs/zbxserver/expression.c    (revision 91057)
+++ src/libs/zbxserver/expression.c    (working copy)
@@ -2712,6 +2712,7 @@
         require_numeric = 0;
         N_functionid = 1;
         raw_value = 0;
+        pos = token.loc.l;
 
         switch (token.type)
         {

Still the real life impact is probably non-existant, as users will not use macros where they are not supported.