Lack of recognition of custom-made LIB CMP files with new software version # 24.1.6.

The new version of LT Spice # 24.1.6 does not recognize my custom LIB CMP files but the older version # 24.0.11 does. For years I have generated custom SYM components stored within custom SYM files along with their associated custom component CMP files. Circuits analysis always worked fine. After downloading the new version of software and not changing any Schematic netlist the simulation does not even start because my custom Schematic symbol components cannot locate their associated spice netlist definition files. I get an error messages "This sub-circuit name is not defined.". No problem analyzing a Schematic with version 24.0.11 but no-go with version 24.1.6.