I've seen something similar in the past, specifically with VPLEX.
I think the issue is on the acquisition side of things, where for some reason (might be related to the firmware version of the appliance) VPLEX reports only Total IOPS numbers - not broken down by read/write. Now, OCI normally would calculate Total IOPS to be the SUM of read/write, but since read/write isn't being reported something seems to be amiss there.
That at least was the case when I last have looked into this. I'm not sure there is a fix for this, but I'd open a case for further investigation. It might be beneficial to have a closer look at the recordings in %SANSCREEN_HOME%\acq\log\storageperformance_<vplex_datasource>_xx_xxxx_xx_xx_xx_xx_xx_xxx.zip wherein you should find the perpetual log files and see if the performance data is broken down by read and write or not.