When is BCBSTX High Deductible Plan G Start date?

In BCBSTX online form titled "Application for Medicare Supplement Insurance Plan" I wanted to sign up for the "High Deductible Plan G" listed on the form which was revised 11/19.  When I call the sales people I am told this is not going to be available until May 1st, 2020.  Why would this be included on a form if it is not available?  The rates are exactly the same as the High Deductible Plan F and that makes sense.  What I do not understand why people turning 65 from January 1, 2020 to April 31, 2020 are being excluded from being offered a High Deductible Plan G.  I think the sale people handle BCBSTX are not talking to the administrative people who are setting up the plans, otherwise this November 2019 form would not list it as and option.  Who are BSBSTX can explain this? Omaha Supplemental Insurance has figured this out and is offering a High Deductible Plan G, but I would prefer to go with BCBSTX.