Only users were matched/migrated. No matched groups in DirSync.
ReACL relies on the presence of 2 files: map.usr and map.gg. If at least one of there files is missing, ReACL will fail.
To resolve the issue, please match or migrate at least 1 group through dirsync, so appropriate mapping files will be generated for ReACL.
1. For the reacl to work, there should be at least 1 group mapped in OD between the 2 environments (source and target)
2. The group on the cloud needs a generated SAM Account name. The types of groups that generate this value are Mail-Enable Security and has to be created from EXO (Exchange Admin Center) - Access M365 Admin Center > Active Teams & groups > Mail-enable security and create a group with the same display name of the one in the On-prem Tenant.
3. Once the groups are matched, you can run the REACL job.
