A Tiger female pregnant with a Liger isn't prepared to deal with this the same way a Lion female is - and maternal investment is way out of whack - resulting in a HUGE cub that grows into a HUGE Liger.
A Tiglon, by contrast is from a male Tiger bred with a Lion female - they are smaller than either parent species because the Lion female is blunting the signal it isn't receiving at the same level from the Tiger male’s DNA contribution.
This is a very common occurrence when you mix a promiscuous species involved in an evolutionary arms race between male and female with a non-promiscuous species that is more ‘peaceful’ in it's DNA.
Yes, I saw them in a documentary.
My brother and his wife went to South Africa recently, and one of the activities on their safari was playing with cheetah kittens. My brother said they licked the skin off his arms just being friendly!