Split year and other country

Hi, I am applying for split year treatment. I easily qualify in terms of number of days spent in the UK. After leaving the UK, I had intended to settle in country A. But in practice, I did not do so. Instead, I lived (and worked) in several different countries. In no other country did I technically become tax resident, until the subsequent tax year. The split year area in the self assessment return asks for the country I moved to. I have been advised that it is not permissible to leave it blank, and yet it seems there is no real correct answer here. Should I put country A? Thank you.

Hi
Please enter the 3 character code for the last country you were in at 5 April 2023.