The issue you are running into stems from Fannie Mae Automated Underwritting system which is flagging your new loan because you have financed a your current property within the last 6 months as a primary residents. Due to this, the system is tell the lender that you maybe committmenting fraud due to multiple primary residents applications within the last 6 months, which you signed documentation in the refinance that you expected to reside in the home for at least 6 to 12 months. I don’t think you are trying to pull a fast one on the lender but that is why it is being flagged by lenders using AUS.
The options for you are to look for a lender that provides a profolio product and will not use an automated underwriting system, or you can wait six months from the date of the refinance loan was sold to Fannie Mae, Freddie or FHA, and start looking for additional properties. Some leaders may allow you to write a letter of explanation but with the likelihood of the lender having to buy back the mortgage is higher than traditional, which make it unlikely you will be able to secure financing under any loan back for fannie, freddie or FHA unless you finance the new home as an investment property.