entities extension update add causes no rows to be effected

in entities extension -> update option/outcome/strategyoptions

when instead of using .state = Added
using entities.Add(...

gets the errors

The database operation was expected to affect 1 row(s), but actually affected 0 row(s); data may have been modified or deleted since entities were loaded. See https://go.microsoft.com/fwlink/?LinkId=527962 for information on understanding and handling optimistic concurrency exceptions.

Start at the entities extension update path for option, outcome, and strategyoptions, comparing entities.Add(...) with setting .state = Added. Reproduce the optimistic concurrency exception and trace the database operation; done means adding through entities.Add(...) succeeds and the expected row is persisted without the error.

Written by the indexing model from the issue text.