The default behavior was changed in the mod so easy mistake. I'd recommend using Ironwail or vkQuake as opposed to the Remastered engine. You won't get the new models in Ironwail but it's the best engine for SP Quake at the moment. IIRC vkQuake will load the new monster models. Neither of these engines will display the new dynamic lights or motion blur but AD will play nicely on both.
Ironwail can be installed easily anywhere on your PC and will automatically find your Steam version of the remaster when launched. I'll have a video on my channel in the next few weeks with many more details but for now you can try these engines out.
Pay attention to the vkQuake instructions and requirements.
Ironwail (0.6.0 and above)
vkQuake (1.20.3 or above)