Activity monitor screenshots below, any thoughts? Top applications using 300-500mb are Safari tabs, Outlook, Evernote.Well, the OWC is for extremely fast USB4 nvme SSDs. For spinning drives I have a wide variety of USB 3.1 enclosures; they all work well at their limited speeds and none of them disconnect or cause mouse problems like you reported. What version of Mac OS are you on? Also look at your activity monitor for any processes that might be using excessive cpu cycles or memory.
CPU - top apps using 2-8% are Safari, Activity monitor, Siri