Plot completed but missing in farm (GUI)

[mattito-uk]

I've been plotting on an internal SSD and farming to two external HDDs but the last plot (finished 4 hours ago) on one of the HDDs seems to be missing in the Plot Count (farm view, I'm using the GUI). There should be 17 plots... I can also only see only 16 plots farming in the Plots view. However, in the Least Attempted Proof table the Plot Passed Filter column values change from 0/15, 0/16 and 0/17 randomly between challenges. Is the Plot Count wrong or is there an issue with the last plot on that drive? Can I continue plotting on that drive or should i restart? I'm using 1.0.5 version. Thanks!