You cant check if a tile in getTiles is a sign by using these 2 things up here, so how can I get it working?
Oh I already got the problem solved by getting the sign as block and then getting its id, but I still wonder why it has entity like IDs and wasnt also recogized as an instanceof the Sign class, even as I dumped the type using get_class() hmm
How to debug: 1. Do var_dump($sign instanceof Sign) to make sure that it is this line that has a problem. 2. Do var_dump(get_class($sign)) to make sure you indeed have signs in your world. 3. Do var_dump(Sign::class) to check if you got the imports right.
So, have you tried `var_dump(get_class($sign) === Sign::class)`? I still believe that you have a typo in your use statement for pocketmine\tile\Sign.