Indents on dice

Hey everyone

Not sure if I asked that before but the dice I make are having some really odd indents around the numbers like the material has shrunk.

Basically the sides are okay but the area around the numbers is lacking material.

Since I only mix small portions I used regular resin as well as UV resin - both with the same result.

Does someone have an idea what the issue could be?

If it is the mold - can someone suggest a good mold I can buy from Germany?