Some users have reported a problem today when attempting to fill gaps in the home timeline. It appears that the Twitter API has changed its behavior today, and is no longer returning tweets when they are requested for a specific range of tweet IDs. We're not yet sure if this was an intentional change to the Twitter API, or if it is a temporary issue.
Assuming the problem is not fixed by Twitter shortly, we're planning to make a change in the upcoming 2.7 update which will hopefully avoid the issue by using a different technique for requesting tweets when filling timeline gaps.
By the way, the 2.7 update is currently being tested and is looking great. Among the new features is support for uploading Twitter videos, access to recent photos and videos from user profiles, and display of quoted tweets within timelines.
Update (June 15, 2015): Tweetlogix 2.7 is now submitted to Apple and is awaiting App Store review. This update includes a workaround for the issue affecting timeline gap filling. The issue has also been reported to Twitter. You can get a general idea of average App Store review times at http://appreviewtimes.com (currently 11 days for the iOS App Store).
Update (June 18, 2015): Twitter has fixed the API issue that was affecting timeline gap filling. The problem filling gaps should now be resolved in the existing Tweetlogix 2.6.1 version.