[BLOCKING] Command blocks data is lost after map is exported in version v1.2.13 768287

*Version: *
v1.2.13 776295

Summary:
Map was exported in version v1.2.13 768287 and then loaded in version v1.2.13 776295
All commandblock data is lost.

Impact:
Unable to test content in latest release.

Repro Steps:
Load the world v1.2.13 749880 press button, no commands are present in the command-block.
Load the world v1.2.13 768287 press button, works!
Load the world v1.2.13 776295 press button, no commands are present in the command-block.

Observed results:
Same happens when I load a version before v1.2.13 768287 aka version v1.2.13 749880.

Expected results:
Command-block data is not lost between versions of minecraft.

Screenshots/videos attached:
World is attached