Applying dye to a sign causes all text to disappear. This happens in at least two cases:

1. Applying colored dye to an unstyled sign
2. Applying a glow ink sac to a styled sign

Steps to reproduce case 1:

1. Create a sign containing some text.
2. Note that sign appears as expected.
3. Apply a dye to the sign.

Expected result, case 1:

The text appears dyed to the selected color.

Actual result, case 1:

The sign is blank, with no visible text. However, one can still apply a glow ink sac to it, consuming an ink sac with no visible result.

Steps to reproduce case 2:

1. Create a sign that includes styled text, for example, §aGreen Text
2. Note that the sign appears as expected, with green text
3. Apply a glow ink sac to the sign.

Expected result, case 2:

The text now appears glowing (bright) green, with an outline

Actual result, case 2:

The sign is blank, with no visible text. 

This may be related to the 1.17.40 release note "Using Dye on Signs that contain formatted color text will now overwrite the formatted color text"