ImmediateFlush setting is ignored in properties-based configuration

All,

I'm in the process of migrating an application from using the log4j 1.x 
API to log4j 2, and I'm still using the old properties-based configuration.

I have set -Dlog4j1.compatibility=trueand so my existing 
log4j.properties file is being parsed, but these settings do not seem to 
have any effect:

log4j.appender.A1=org.apache.log4j.DailyRollingFileAppender
log4j.appender.A1.File = [...]
log4j.appender.A1.Append = true
# Spell this both ways, since log4j2 seems to Really Like PascalCase
log4j.appender.A1.immediateFlush=true
log4j.appender.A1.ImmediateFlush=true

The behavior I see if that if I use tail -f to "watch" the file, the log 
messages come out in chunks, likely when a buffer has been filled and 
flushed. The messages are cut-off mid-message and are not up-to-date 
with what the application has logged.

When switching to XML-based configuration, the "immediate flush" 
behavior is working as expected.

I'm using log4j 2.17.1.

I'm prepared to switch-over to using XML-based configuration in general, 
but making this work will certainly improve the migration path for 
lingering users of log4j 1.x.

Thanks!
-chris