As a guess this is an issue with the target and how it was shutdown.

Here is a link on WIJ recovery.

You are using Unicode. On my 8 bit install it stops after 255.

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

8 bit or 16 bit storage option on install - https://docs.intersystems.com/iris20252/csp/docbook/DocBook.UI.Page.cls…
Different character set for the locale - https://docs.intersystems.com/iris20252/csp/docbook/DocBook.UI.Pag
e.cls?KEY=GORIENT_localization#GORIENT_localization_locales or Configuring National Language Support (NLS)

Could even be different character sets in the terminal settings to the linux servers.

As a guess the routine is returning 1 and you can demo this using @Dmitry Maslennikov suggestion:

run do $zu(4,$job,1) and check errorlevel

run do $zu(4,$job,0) and check errorlevel