[2023] No progress transfer

Hi there, based on the information available it sounds like you are describing a Link, not a Merge. 
 

On 2023-12-12 at 10:11 AM, [DE]CoreyOnline said:

Any Warframe account that was previously involved in a PC-to-console account migration to PlayStation 4, Xbox One, or Nintendo Switch is ineligible for a One-Time Account Merge. However, these accounts can still be Linked normally and participate in Cross Platform Save.

Had you ever participated in a PC-to-console account migration (to PlayStation 4, Xbox One, or Nintendo Switch)? If so, the PC account is not eligible for Merge but can still be Linked.