Answer: In a Parade Magazine article and interview with Tom Selleck in May of 2020 was the following update:
"Selleck is spending his lockdown on his 63-acre working ranch in Ventura County, Calif., and the good news for Jesse Stone fans is it is giving him time to write the next installment of movies based on character created by Robert B. Parker, which already has a deal at Hallmark for No. 10."