OK I'm not going mad, here's how to reproduce texture lock bug in A7.50.
1. - New map
2. - add cube small
3. - add another cube small
4. - Place cubes next to one another butted together.
5. - Apply default texture to both cubes.
6. - group the 2 cubes.
7. - Set Texture Lock On, in object properties for group.
8. - move and rotate blocks.
9. - open build dialogue.
10 - Either build or cancel build it doesn't matter.
11 - Click in any WED window.
12 - You should now have jumbled texture allignment.
Tested on 2 machines with A7.50

Jethro.