Presence of 20% of starting material le. structure of the starting material 1. The fist process (A)'O would be operative with an acetal such as IC or a ketal such as Id where an intermediate carbocationic species is stabilized while the second one (B) concerns the aliphatic acetals la and lb, which need lithium iodide to be converted to the parent ketone (the comparison of entries 1 and 2 and of entries 4 and 5 argues for this hypothesis). ...
