Can someone help me understand what type of user error (?) is going on here please?

One one system, I write out a group of $c() values and get the expected results:

USER>for i=250:1:260 { write i," ", $c(i),! }
250 ú
251 û
252 ü
253 ý
254 þ
255 ÿ
256 Ā
257 ā
258 Ă
259 ă
260 Ą

USER>w $zv
IRIS for Windows (x86-64) 2023.1.4 (Build 580U) Fri Apr 19 2024 11:16:07 EDT
USER>

On another system, I get some unexpected results:

2 3
1 65