Review form input lost on save/submission? OJS

I hate to ask a question so vague but this is on behalf of one of my editors, who reports that two peer reviewers in recent months have “completed and submitted” review forms but that these were “lost in the system.” I’m trying to figure out if I can rule out system error.

One of the reviewers says: “Spend a consider amount of time filling out the online form and then when I went to submit review it lost all my content.” I checked the review history and review details and don’t see any evidence of this in the logs and was not able to replicate the error myself. The reviewer forms have not been altered. I don’t know about the other reviewer; there’s a chance that person tried to complete their review in OJS prior to the upgrade.

I suspect the cause might be user error. However, I’d also like to ask around to see if anyone else is running into problems like this or if there’s something I ought to be doing to troubleshoot.