Apolozy for the delayed reply, as we were out of office during the weekend.
Thank you for providing the details regarding your setup. Yes, the components you've listed — SP Page Builder Pro 5.5.7, Helix Ultimate Template v2.1.2, and Helix Ultimate System Plugin v2.1.2, installed on a clean Joomla 5.3.0 environment — should indeed meet the minimum requirements for importing a page layout.
To better understand the issue and assist you more effectively, could you kindly share a screen recording of the entire process you're following and the exact issue you're encountering? This will help us identify any potential missteps or configuration problems.
Looking forward to your response.
Best regards