People Counting Camera Sending Email But No Attachment

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I've installed three of these cameras, DS-2CD6825G0/C-IS, two are at S/W level V5.5.90 build 200728; the other is at S/W level V5.8.10 build 230810. As it turns out, the two cameras at V5.5.90 operate flawlessly in sending daily emails with an attached data file; however, the other camera sends the email but no attachment. I've gone over all config settings, ensuring they match the working cameras and to no avail. I think I read somewhere that this is a known problem. My question is, can anyone shed any further light on this and a possible solution? Thanks in advance.