Saved Text Changes are Lost by Changing Print Format

Expected Behavior

Saved text changes are maintained when Changing Print Format.

Actual Behavior

Saved changes to a text file are lost when Changing Print Format.

How to Reproduce

1. Launch OpenPad 1.5.1 on Android 8.1.0
2. Open an existing text document
3. Click the Pencil icon to Edit
4. Add some text to the document
5. Click the Disk icon to Save
6. Click the Three Vertical Dots
7. Click Change Print Format
8. Click UTF-8

Device: Pixel 2 XL
OS: Android 8.1.0
App Version: 1.5.1

Recording of the Bug