I created a Nether Portal in the Overworld, at these coord:  

-595, -57, 1225

Went into the nether. Died in the nether. Re-entered the nether - no issues.

But, after returning to the overworld through the Nether portal (located at:  -77, 35, 170) I was placed underground at a different location at these coordinates.  This is the 2nd time this has happened in new worlds under this version.  The "wrong" portal coords: 

-600, 23, 1344

I haven't seen this behavior before in other versions.

The portals weren't blocked or obstructed by anything. I am using the datapack for the caves/cliffs update.

After breaking the wrong portal in the overworld, going into the nether and returning, it placed a new portal (again in the wrong position) at: -614, 63, 1365