Odd Issue found in Pokemon Pearl Version

[ExtraNicc]

Hello, so I've come across an oddity in playing Pokemon Pearl. I've had this for a while, but since I messed with the save data externally a lot, I assumed it had to do with that. But upon resetting the file and grabbing the explorers kit, the same thing happened.

The issue is, whenever I use the explorer's kit, I can descend into the underground just fine. However, upon ascension, the game will freeze on the white screen, unable to do anything until I turn on and off the device again. Is there a reason why this is occurring, and more importantly, any way to fix it? Feel free to ask for more details and I'll try to answer accordingly. Thank you in advance,