Yes they all seem to be missing in 1901
. Could be a mistranscription but I've tried quite a few variations.
Their names must be really badly mis transcribed I've tried every combination I can think of

Are there any missing censuses pages 1901 Manchester? Perhaps they are using a different name altogether

This appears to be his christening (familysearch.org) - residence 1898 Manchester Lancashire
perhaps finding their address 1898 may help locate them in 1901
Stanley Misell bapt. 12 Nov 1902 St. Thomas, Manchester birth date: 04 Jan 1898
father's name: Bryman Misell mother's name: Harriet
indexing project (batch) number: C03554-7
system origin: England-EASy
source film number: 2113152