[SOLVED] "Startup" is missing from the left-hand menu in "Settings >> Apps and features" ?

Solution
Settings shouldn't change themselves, could be a program is over riding your choices

Try a clean boot and see if it changes anything - make sure to read instructions and make sure NOT to disable any microsoft services or windows won't load right - https://support.microsoft.com/en-au/help/929135/how-to-perform-a-clean-boot-in-windows

It doesn’t delete anything, it just stops non Microsoft programs running with start. Easy to reverse.

if clean boot fixes it, it shows its likely a startup program. You should, over a number of startups. restart the programs you stopped to isolate the one that is to blame.
Settings shouldn't change themselves, could be a program is over riding your choices

Try a clean boot and see if it changes anything - make sure to read instructions and make sure NOT to disable any microsoft services or windows won't load right - https://support.microsoft.com/en-au/help/929135/how-to-perform-a-clean-boot-in-windows

It doesn’t delete anything, it just stops non Microsoft programs running with start. Easy to reverse.

if clean boot fixes it, it shows its likely a startup program. You should, over a number of startups. restart the programs you stopped to isolate the one that is to blame.
 
Solution