Hello Alex,

Here's how I finally resolved my issue:

1. Upgraded to zOS 3.1.

2. Upgraded to IBM Java 21 (which has different file encoding semantics than Java <= 17 - I was formerly using Java 11).

3. Found this Java file encoding snippet on the IBM Web site:

https://www.ibm.com/docs/en/semeru-runtime-ce-z/21.0.0?topic=guide-file-encoding-utf-8-as-default-charset

4. I think I had previously put -Dfile.encoding="IBM-1047" in the ant script as part of $ant.sys.options.

 I removed it (and temporarily added -Dcom.ibm.autocvt.trace=true  just to do a verbose check).

Viola - all tagged files (e.g., via .gitattributes) converted internally to UTF-8!

This was a Java issue all along; -Dcom.ibm.autocvt was disabled because ant specified -Dfile.encoding="IBM-1047"

(and Semeru, being higher than Java 17, acted differently than my former Java11).

Again, thanks for your input - it helped to clarify the issue.