Hello,
For me it's normal if you can't add users from the trusted domain into a global group in the trusting domain it is not supported
https://learn.microsoft.com/en-us/windows/security/identity-protection/access-control/active-directory-security-groups
So you will have to use domain local groups in the trusting domain in order to give access, you should also check if authenticated users is used on your network shares because trusted domain accounts is member of this group :
https://social.technet.microsoft.com/Forums/windowsserver/en-US/39f0d1f2-966f-4e24-b92e-c837ce0ccd1a/use-of-nt-authorityauthenticated-users-within-a-forest-trust?forum=winserverDS
You should check the trust configuration to ensure that SID filtering is disabled
https://social.technet.microsoft.com/Forums/windowsserver/en-US/53e615da-48bc-418e-85ee-bf9fb30c6104/how-to-see-sid-filtering-is-enabled?forum=winserverDS
Regards,