PC [BUG] My close friend has disappearing furnaces, and maybe all of her items are disappearing!

[EverOptimist]

Stardew has had such a positive impact on my life, and now I think it's having a wonderful impact on my friend, who has really bad anxiety and depression, and who seems really at peace when she's playing this game. But now she's getting an awful glitch!

1. Furnaces don't work. She knows the whole process. Sometimes they take her ore and then don't do anything.
2. Her furnaces are disappearing. She's even tried placing them inside. She's not married, so it's not a spouse walking into them.
3. I'm worried this will apply to other items she places, since these are the first items she's placed on her farm aside from chests!

Can someone please help? She plays Stardew all the time and I really want her to have a lovely time with it!