We have the exact same issue with 12x of the NEWER version of this exact camera ( ours are a ~600$ ip cam) the IB8382-T ... EXACT SAME ISSUE only a few days after install on 3x.. (actually we had been using Vivotek IP cams for nearly 9 years, and never had any issues at all, 200+ installs of them, quite a few still online and looking great today).
on the recent job / issue, its Def. not the installers fault or a single supplier issue, as our client wanted 4x of these, then about a month later wanted 8x more (and + 10x more of the IB8369A (~240$). So These were from entirely different suppliers , and all ended up having the same water intrusion / moisture issues. (at this point we have to have techs go to each cam and dump water / change discessent bags 3x times over past 6 months. $$$
After trying very hard, and getting zero reply from vivotek, i figured, let me try email blasting support + the executives. Not sure if that was the reason or if just luck, but i did finally get a reply from support this time. After he researched it, he came back with "there was a manufacturing issue/defect we discovered at one of our camera plants, and for about 6x Months of production, many of that model camera (ib8382-T) were shipped/made without proper glue or sealent on the front lens". (i think the issue is deeper , as after a hard rain/wind storm some of the "unrelated" $240 8369a also had moisture issues for the 1st time). All of these cams have been deployed less than 6 months now
they offered to replace the cams , so im now trying to follow up on that, as this email conversation was 2 months ago ( however again, im not getting any replies). In the mean time, 2 x more vivotek DOMEs we have installed have had moisture issues, so that was the last straw for us and vivotek (honestly, its a bit sad, as we were super happy with them for the past 8 years).
we have since moved to Axis IP cams recently and have been SUPER impressed with the build quality and the DEEP capabilities of their software (not sure how we hadnt used their cameras before).
IMO vivotek has decided to slash costs on MFG to try to compete with all the cheep crap IP cam mfgs that are so common place now.. this is just my opinion, no proof... but its really sad, as they used to have GREAT products and GREAT software. (they still have great SW)