Can insurers reject ported policy claims?

I have been continuously insured under a health policy since 2020 and recently ported my plan to another insurer without any break in coverage.

- Shilpa Arora

A few months later, my hospitalization claim was rejected on the grounds of nondisclosure of a preexisting condition—acidity and heartburn that I had before taking the original policy. Since my coverage has been continuous for over four years and the portability process was done correctly, is the insurer justified in denying the claim? What steps can I take to resolve this?

—Name withheld on request