Truetype bitmap font, for embedded UI design, stopped working in latest Photoshop 2024

I use a set of custom TrueType fonts for embedded-system UI design. Bitmaps generated from these fonts are used in the actual embedded-system UI. The system has a low-resolution screen, just 128 x 64. I use Photoshop to allow pixel-accurate designs, with a 128 x 64 pixel canvas. I've used this method over the last five years for several popular products.

I created the fonts in FontForge; they have both outline and pixel elements. They are very small, with the main body text being 8 pixels high. In previous versions of Photoshop, the fonts displayed correctly on the 128 x 64 canvas; when I set the size to 8 pt, it used the appropriate bitmap. 

I had not loaded the document for a few months. When I opened it in the latest Photoshop 2024, 25.4.0 release, Photoshop showed a message that text layers needed to be updated "for use in vector-based output." After the document was updated, the text was completely garbled, with many characters stacked on top of one another. I closed and re-opened the document, and this time declined the text layer update. Previously created text appeared properly. However, when I double-clicked on a text layer, it immediately collapsed into the same garbled state, as if all characters in the layer were stacked on top of each other.

This is an important workflow for our product development, and it's quite inconvenient for it to be suddenly broken. I am happy to provide the fonts and an example document to Adobe support personnel, but cannot post them publicly. Screen-shot shows part of a document; readable portions are text layers which have not been clicked on, and garbled portions have been clicked on.

Photoshop 2024, 25.4.0 release
Platform and OS version: Mac Studio M1 Ultra, macOS Ventura 13.6.6