Very common problem with silkies, especially those with large crests & beard.
Also very common in nests not deep enough(for any breed or mutt) and/or don't have suitable nest material, and also common with hens given/allowed to set on too many eggs. If you are seeing any egg, that is too many. Also have to make sure all eggs are actually directly under and touching her breast and sides below the feathers- eggs not under her body but covered by a wing are not actually being incubated, that is too many eggs too.
Also common with nests where other hens have access.
Solution: Isolate nest from all other birds, make sure nest is good- not flat and has material the hen can actually use to "weave" a rim around her. Limit number of eggs- a lot of people are too optimistic about how many eggs a hen can really cover.
To be fair, there are hens who are just better or worse about making sure eggs are under her.. still, with a nest deep enough and right materials, even the "lousy ones" will be able to bring off a decent or excellent hatch.