Same issue here on a Dell Inspiron 13-7378 (ALC3253).
Audio was working fine on the previous kernel (4.15.0-96-lowlatency) and after update to 4.15.0-99-lowlatency there is no sound from the internal speaker and also the mic is not working. The sound works fine on an external USB device (plantronics P610).
Same issue here on a Dell Inspiron 13-7378 (ALC3253).
Audio was working fine on the previous kernel (4.15.0- 96-lowlatency) and after update to 4.15.0- 99-lowlatency there is no sound from the internal speaker and also the mic is not working. The sound works fine on an external USB device (plantronics P610).