I've noticed this in P12 & 13 and maybe even versions before that. If I apply a tex file as a mat and then I subsequently make a change to that tex file in my graphics app, I have to disconnect the node and replace it with any other tex file (doesn't matter what), and then save my update in the graphics app. I think I save my scene, too (I save it often). I then reconnect my updated tex file to the node. That way my change updates in the render (if not in the preview). I can't recall having any luck with Reload Textures.

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W11,Intel i9-14900KF @ 3.20GHz, 64.0 GB RAM, 64-bit, GeForce GTX 4070 Ti SUPER, 16GB. 

Old lady hobbyist.

All visual art or fiction is "playing with dolls."