Yes and no. Here is the basic rundown of the current situation with UMC and workshop maps:

• UMC uses keyvalues to create its complex mapcycle file and structure (which is why it has a robust feature set).
• As of UMC 3.7.0, CS:GO can use workshop maps but only if the server is running on Windows OS. This is due to CS:GO requiring the use backslashes "\" when processing the maps on Windows.
• TF2 (regardless of OS) and CS:GO Linux both require forwardslashes "/" and keyvalues seems to consider this a separator for two different keys. This is most likely the main reason this does not work at all for TF2 and CS:GO on Linux.

While CS:GO on Windows can use workshop maps with UMC, TF2 (all platforms) and CS:GO on Linux cannot do so at this time. Because the problem is complex, it will require more time to solve and possibly significant changes to be made in order to get the maps to appear properly in menus and to ensure they are formatted properly for map changes. This is currently in the works, but for those of you enterprising enough to take the coding end on yourselves, know that the answer lies within keyvalues and the forward slashes, which currently seems to be the primary issue with UMC and workshop maps.

As far as other games with workshop support, the same issue will apply in most cases! Your best option at this time, when using UMC, is to utilize fast download and have users download maps that way rather than through workshop.

The following is (or will be) the proper format for the map names in UMC:

CS:GO (Windows)

workshop\32898198293\<map name>

CS:GO (Linux)

workshop/32898198293/<map name>

TF2 (All platforms)

workshop/32898198293/<map name>

Please note that, as of 8/14/2019, workshop maps only work with CS:GO on Windows servers only! CS:GO Linux and TF2 (all platforms) will not work!

The most likely culprit is that the map you're nominating has a different group name than a group that's actually in the vote. This commonly happens when you have separate groups for voting/nominating, and it happens more often when there are separate UMC-Mapcycles for voting/nominating.

To fix this, you can specify which group a nomination should belong to by using the nominate_group option, outlined in the documentation for the Core Module. This way you can set which group nominated maps belong to without altering the structure of your nomination groups/mapcycle.

You probably forgot to set maps_invote in your UMC Mapcycle definition. This option specifies how many maps from a Map Group to be included in a vote. If it is not set, it defaults to 1.

There are several versions of GunGame around. The one recommended for use with UMC is the SourceMod variant, which you can download here. To use UMC with SM GunGame, first make sure the Vote Command module is enabled and configured. Then, add the sm_umc_mapvote command (with appropriate arguments for how you want the vote to run) to the gungame.mapvote.cfg GunGame configuration file, located in the cfg/gungame directory.

Valve has this functionality built into the Source Engine. If you set the console variable mp_match_end_at_timelimit to 1, then all maps will end the second the time remaining reaches zero. This console variable defaults to 0.

If tiered voting is not working or is showing incorrect maps, you will need to add the playerlimits module. The umc-playerlimits.smx module is necessary for some tiered voting and groupings depending on the options used.