Sorry, but I have to ask this question again about the same problem. Using several snippets, but it can be easily reproduced with “4x4 wipe” in FM 6.0b35:
If you insert pictures into the fields A to D, you can select these fields, but you can’t delete them together, even though they don’t have a lock symbol. Not even with right-click. In the meantime I have found out that each slide can be deleted with a right-click, but not all at the same time. A rather tedious procedure, so as a workaround I open the file with FM 5.x, where there are no problems with deleting.