The texture for the beacon's beam in the 4J Studios texture packs (city, plastic, candy, etc.)is loading the default texture instead. This is because instead of the necessary file being located at entity/beacon_beam.png, it is located at entity/endercrystal/endercrystal_beam.png

The following tests were made by accessing pack files on Windows 10:

Candy and plastic texture pack returned positive with beam in previously stated location

Festive mashup contained actual crystal beam file in entity/endercrystal.

Could not access Halloween mashup assets due to pack encryption