Based on investigation following community feedback we are rolling back the following change to its 1.5 behaviour:

• Fixed an issue where car part design and research projects were not generating the appropriate amount of expertise gain when the sliders were moved

This reversion will only affect the above, all other 1.6 changes will remain and this will work with your existing saves so there’s no need to restart your career!

We'll be investigating this issue further and will have more news on this soon. Thank you for your continued feedback and support!