I get the impression LatencyMon can interfere with xperf traces so please uninstall it, reboot, and continue with xperf for now. I'd also delete kernel.etl from the root of your system drive. It is supposed to just be a temporary file used by xperf. I'd suggest using the attached script to capture another trace as it will keep the trace below 300MB no matter how long you run it (it creates a circular buffer in memory rather than continuously writing to a file). It's possible writing the trace to disk during the capture is interfering with the disk I/O performance readings. The kernel.etl file will likely reappear when the script is run but don't delete it; at least not until it's finished merging out the trace as explained below.
Extract the .cmd file from the zip to your Desktop, right-click that script icon and select "Run as administrator" and a command prompt window should open. Press a key to start the trace and leave the command windows open running in the background. Use the system until you experience the issue you're having and switch back to the command prompt window, press a key, and the the trace should be merged out to a file on your Desktop named "trace.etl". It's about a 30 to 60 second circular buffer so you should have plenty of time to switch back to the command prompt window after reproducing the issue. Please zip up the trace.etl file and make it available for download. It will likely be too big to attach so you might need to use a cloud drive or file sharing service.