Doesn't Inzecter Damsel effect can be missing time.

I have played on inzecter player's alot they said they get damsel's summoning effect When It's Inzecter Hornet effect active .

No it won't miss timing. Even tho it's an optional effect.

I really don't understand can someone make clear my mind.

The difference comes within the fact that the card text currently says "If" and not "When."

Same scenario that we had when Light Pulsar FTK was around.

the trigger effect that have "if...you can..." don't miss the timing.
The condition only need happens to be able to active the effect.
"when...you can.." you need active the effect in the moment the condition happens, so you can miss the timing

"If" effects don't miss timing
Mandatory Triggers (doesn't say "can") don't miss timing.
"When... can..." effects are the only effects that miss timing.