Flat add-blocks don't trigger minecraft:on_step_on component

Partner Rank: 3

Partner Team Reporting: Jigarbov Productions

Verification builds: 1.16.100, 1.16.201, 1.16.210, 1.16.220

Summary:
Flat add-blocks don't trigger minecraft:on_step_on component

Impact:

makes the utility of the on_step_on component less usable and inconsistent

Repro Steps:

1. install the repro resource/behavior packs
2. enable holiday features
3. do /give @p design:disco_floor
4. and do /give @p design:flat_disco_floor
5. place both blocks
6. jump on both blocks

Observed Results:

the full size block correctly triggers on_step_on and changes the block permutation. the flat version of the same block does not. this break in functionality is somewhere between unit size 3.2 and 3.4

Expected Results:

both should trigger on_step_on 

Regression Builds: never worked since add block was added

Notes: