I have something really obvious when I take the exact value you display :
Invalid values
I12
Archer, Cornelius (°4 July 1853 +) INDI:BIRT:DATE doesnt contain a valid value
I13
Archer, Edward Sylvester (°26 July 1855 +) INDI:BIRT:DATE doesnt contain a valid value
I5
Archer, John William Walter (°26 July 1852 +) INDI:BIRT:DATE doesnt contain a valid value
I6
Archer, Thomas William (°26 August 1856 +) INDI:BIRT:DATE doesnt contain a valid value
I9
Archer, Sarah (°September 1846 +) INDI:BIRT:DATE doesnt contain a valid value
When I correct the date, the tree is in correct order after a redisplay.
Zurga