Costumer Names in UTF

When creating costumers i can create with the letters ø,æ, å and the look fine.

When creating a new qoute, they are displayed but NOT with ø, æ, å

And if i choose one of the wrongly displayed costumers, invoice plane creates a new costumer.
https://community2.invoiceplane.com/uploads/default/original/1X/0f8abeac7a5ea218e6cee64e54a09fb05593c713.jpg

https://community2.invoiceplane.com/uploads/default/original/1X/5a40222497e1c93d0a1adc562763dea131909e80.jpg