Tempo change audio file after importing in WL 10

When I import an audio file in WL 10.070 the tempo changes if the master section is disabled. Also I hear cracks in it. The files are all 48 KHz, 32 bit floating.
In the master section they are resampled to 44.1 KHz and 16 bit. If I turn the master section on, the audio files play normal.
If I import a file with 44.1 KHz and 16 bit, it plays normal, with or without mastersection enabled.

Anyone an idea what is happening? Never had this issue before, and I work with Wavelab since version 2.