Downloading Soundpacks shows "X out of -1.0B"

[Brambor]

Describe the bug
Downloading Soundpacks, even though Launcher knows the size, in download progress it says x / -1.0B (see the screenshot).

To Reproduce
Steps to reproduce the behavior:

1. Go to Soundpacks
2. Click on some to download.
3. See that it loads soundpack's size.
4. Start downloading it
5. Look down to see X out of -1.0B

Expected behavior
See out of soundpack size and see the progress bar working.

Screenshots

Desktop (please complete the following information):

• OS: Windows 10
• Version 1.5.6

Additional context
None.