GA4 Google Analytics event doesn't appear as conversion

I'm using Google Tag Manager(react-gtm-module) package) to push custom events to Google Analytics. In code i do it like this:

GTM.dataLayer({ dataLayer: { event: 'Custom event' } });

Then, in GTM i have trigger for this Custom event (event name is the same everywhere) and tag which sends event to Google Analytics. Then in GA i marked that event as conversion, but when i trigger that event on website it shows up as regular event but not as conversion.

This works perfect for every other event but not for this one. I tried to rename event and mark new event as conversion but it didn't help.

Could anyone by any chance know the reason why it doesn't work as expected only for this event?

I am not sure follow the actual issue you are having but you're missing a ' in your code after the event name

this

GTM.dataLayer({ dataLayer: { event: 'Custom event } });

should change to

GTM.dataLayer({ dataLayer: { event: 'Custom event' } });

Otherwise, are you saying that you are specifically using the string "Custom event" as the event parameter value? Perhaps that is a reserved value in the system used for something else, but it seems unlikely.