This is an issue in SMSQL 6.0, the bug number is 665306. There is a workaround, and I think the problem is also fixed in 6.0.1. For the quick workaround, here I quote:
%%% TITLE: SnapManager for SQL Server (SMSQL) shows 0 transaction log backups available to be restored, although log backups are available
During a restore process using the SnapManager for SQL Server GUI, several databases display 0
Transaction Logs, even though the logs have been backed up and are visible in the snapinfo
directory. Because there are no log backup copies shown as available to be restored, no up-to-the minute
or specific point-in-time restore operation can be performed.
From "Restore setting", enable "Ignore Logbackups from SMSQL repository
SMSQL 6.0 introduced SMSQL repository share, where the log backups can
be copied to a share and those log backups can be used by a different
system. This feature is mainly for SQL Server 2012 Availability Group
database gapless restore functionality to allow up to minute restore
on any node of a cluster.
This option will only search for log backups located on the local snapinfo
directory and ignores log backups in the share when trying to enumerate
If you are not using SQL Server 2012 AG (or you do not use SMSQL
repository share), there are no side effects in using the workaround