An Empty Ad Group Issue means an ad group is switched on but can't run, because it has no ads or no keywords. It covers Google Ads and Microsoft Ads Search campaigns, and Meta Ads ad sets with no ads.
Fix it
Open the Issue to see which ad group it is.
In the ad platform, add ads or keywords, or pause or remove the ad group.
Back in Opteo, click Recheck, for example Recheck Google Ads.