Just had a chance to look at the font assets you provided.
The MSB font asset doesn’t contain any characters or glyphs so not sure if that was an export issue or the actual state of the font asset in your project.
The MSBL font asset does contain characters and glyph so it appears to be fine. However, given this font asset is assigned as the bold font weight to the MSB font asset, we’ll need to fix the MSB.
I am not sure if the MSB font asset contained the same characters and glyphs as MSBL. Assuming it did, it is pretty simple to regenerate this font asset. It also appears the material presets still reference the empty atlas texture of the MSB font asset where updating the font asset should update these presets as well.
To regenerate the MSB font asset, I simply used the Font Asset Creator using the MSBL as reference to include the same characters and glyphs.
I used SDF16 but noticed that your MSB was using SDF and the MSBL using SDFAA. Not sure what was the original sampling mode of these original font assets. Do you have a backup of these?
After the regeneration, the material presets maintained their reference to the parent font asset atlas texture.
I noticed that your material presets are using maximum values on many of the material properties which is likely what was leading to the issue you initially posted about. Basically anytime these material property values are near 1, you are essentially at the edge of the adjacent glyph in the atlas texture. At certain zoom factor and due to bilinear filtering, you will get that ghosting / visual artifact in your screenshot.
The Sampling Point Size to Padding ratio determines the effective range of material properties. For example, if the Underlay Offset X value is 1 (max) at a 10% ratio, increasing that ratio to 20% would double the distance / effective range of that shadow. However, in both cases you are still at max value of 1 where this visual artifact can occur.
The idea behind increasing this ratio is so that you can use smaller material property values to achieve the same visual look while using smaller material property values thus keep you well inside the padding between each glyph in the atlas texture.
Whenever you create a font asset and end up using material property values near their maximum, it is a sign that your sampling point size to padding ratio is too small as you are pushing everything to the maximum.
Here is an example of the same font and material with 10% vs. 20% ratio with the same values.
Notices how the outline thickness is 2X with double the ratio.
Since I am not sure what your original sampling point size and padding were on these font asset prior to the upgrade as well as what Atlas Render Mode you were using, I would suggest going back to a backup to verify this information.
Since the issue you initially reported appears to have been caused by using material property values at their max range, either decreasing these values or assuming you want to preserve the same visual appearance then increasing the ratio of sampling point size to padding from something like 10% to 15% for example would enable you to reduce these material property values to maintain the same visual appearance while staying without getting to the edge of the adjacent glyph in the texture.
P.S. When using fallback font assets, you want to keep the same sampling point size to padding ratio in order to maintain the same visual appearance at the same material property values. Although the sampling point size and padding can change, as long as the ratio is the same that outline thickness for example will appear the same between those font assets.
Hopefully, this gives you enough information to update your font assets and resolve this issue. Keep me posted please.
