Performance Document - Japanese Comment disappears after saving

Hello Experts,

We are currently facing a weird scenario regarding the Mid Year Performance Review for Japanese employees.

Basically, when employees write with Japanese characters, it shows a "predictive" box with Japanese words, as it is some kind of suggestion. Then, when they select the words and click 'Save and Close', the comment is not there apparently. However, if it is with "normal" characters, the content is saved. Please refer to the screenshots below from "Before Saving" and "After Saving".

Do you have any idea if this could be something related to Oracle or could it be from employees' laptop/keyboard/browser located in Japan?