Post compatibility issues here. 

There's a patch file on the download page that you should get: https://himeworks.com/2020/08/grid-battle-engine/#patch

Yanfly Engine Core. For grid selection,

1. Attack enemy, enemy dies 
2. select tile that enemy was on, enemy sprite suddenly appears again
3. Attempt to attack it, nothing happens. The enemy is still dead, just a visual bug

Issue occurs in function Sprite_Battler.prototype.updateSelectionEffect on line  2068, where it forces the target to be highlighted, which probably causes it to re-appear.

Victor Engine Basic Module

All battlers have ID's for their sprites. Tiles need to have it included as well. Patch file has been updated to include this fix

// Victor Engine Basic module. Each sprite is identified by a unique ID
Game_TileBattler.prototype.spriteId = function() {
  return 'tile ' + String(this.getBattleNode().id);
};

You can add it manually or just grab the patch file.

Yanfly's YEP_X_StateCategories

Area of Effects from HIME_GridTargetArea were being loaded before the game objects were created, which caused issues. This will be fixed in the next release.

Loading from save files crashes the game. Problem is described here

https://forums.rpgmakerweb.com/index.php?threads/how-do-i-define-custom-objects-in-save-files.126201/

For MZ, there were issues with circular references: Actor holds a Tile object, which may reference the actor itself.

This has been fixed and will be available in the next release.