Local-adjustment presets saved with default tone curves won't reset tone curves back to the default values.
To reproduce on LR 13.1 / Mac OS (see the attached recording):
1. Make a Linear Gradient mask.
2. Save a local-adjustment preset named Clear.
3. Change every setting in the local-adjustment panel, including the tone curves.
4. In the Preset menu, select Clear.
5. Observe that every local-adjustment setting has been reset back its default value except for the tone curves.