Could use confirmation, fixes and checking if the following are still present in the more recent firmware versions:
USB flash drive
If you save more than 10 files to external USB flash drive, thereafter at some point you'll get a file error. You may be able to still save files, but some of the files will be corrupted.
Is there a safe way to remove the USB flash drive other than powering off the Rigol? Whether Rigol's functions are turned off or on, and the USB drive is not being accessed, removing the USB flash drive with the Rigol powered on crashes the Rigol. Its ok to insert it, but not remove it.
FFT
After over 1 hour of use, or after the file error with the USB flash drive, new harmonics appear in the FFT spectra. If you shut off the Rigol or reset to factory defaults, these harmonics disappear, and the distribution is what is expected, say with testing with a square wave.