Solution:
This MAP error is a known issue on Radiant 2024.1 SP1 when designing with Avant PCIe IP pcie_x8 v2.0.0 for LAV-AT-G70/X70.
To resolve this error, install the patch on top of Radiant 2024.1 SP1 (R2024.1.1.259.1_patch23590.zip).
FTP link: https://latticesemi.files.com/f/50ac3b8345907d5f
This issue has been fixed in Radiant 2024.2.