Primary residence HELOC for a new primary residence down payment

Hi, Im in the process of having a HELOC opened on my primary residence (Property #1). My plan is to move out in a couple of months to turn my primary residence into an investment property and use the HELOC for downpayment for my next primary residence (Property #2). Question, would I have any issues on doing that, considering the HELOC was applied on a primary residence (#1)? I already talk with the HELOC agent and for them it wouldn't be an issue as long as I don't sell my first property (#1); but speaking with my mortgage lender (for property #2) they told me I wont be able to get a primary residence home if I have that HELOC (primary residence terms) opened for less than 1 year.

Any thoughts on this?

Thank you in advance