Could be many different reasons, but it's difficult to say because I don't really understand who/where this "Monica" works...I can't quite understand if she works at the real Huisun manufacturing company or if she is simply a reseller of the Huisun brand or if she has a company that makes "knock off" Huisun cameras.
What I understand to be the manufacturers website lists no "Monica" as a contact person. It says they started in 2013 and have 2 headquarters. One in Tianjin, China with the contact person being Melody Wang...The other in Shenzhen, China with the contact person being Lucy Zhai.....Alibaba profile says they employ between 11 and 50 people with a total annual sales volume of $2.5 to $5 Million dollars. Also says they produced 100,000 units in the previous year.
Someone that knows what they are doing could easily screw the parts of a PTZ cam together in 10 minutes....but if this really is the legit Huisun manufacturing plant and they're producing 100,000 cameras a year on other distribution lines outside of Aliexpress, then I could understand the production delay...Could also understand the production delay if it's a "knock off" company with one or two people putting generic parts together with similar specs to Huisun brand cameras.