Why can’t I always preheat the chamber from Creality Print, Creality App, or Fluidd?

Sometimes I can preheat the chamber from Creality Print, the Creality App, or Fluidd — but other times, the option is just not available or doesn’t respond. I can’t quite understand the logic behind it.

I’m trying to preheat the chamber to soak before printing some Elegoo Rapid PETG. I’ve already done this successfully before, with flawless results, but I’m always looking to push for even finer prints.

The issue is: sometimes the chamber temp setting works just fine, and other times the printer doesn’t respond, or the setting box is missing in Fluidd.

Does anyone understand what might be causing this, or what the correct steps are to consistently get it working?

BTW, I received my K2 Plus on May 26th and I’ve logged 19 days and 15 hours of printing so far — with mind-blowing results. Super happy with this beast.