Battle For Windhelm won't start.

[WardenMahariel1995]

So, after playing through the already quite buggy Imperial Quest Line (Serves me right for fighting for the Empire), I'm now stuck completely. After completing the battle for Fort Amol, the quest now guides me to Legate Rikke to receive my new orders, presumably for the battle of Windhelm. She gave me my pay for the Battle at Fort Amol, but now only keeps saying that we're taking the city and to "move it!" The quest for Fort Amol ended, but the battle for Windhelm won't start, only telling me to report to Rikke with her repeated dialogue. I also tried console commands, but it keeps saying "LocAliasIsLocation" followed by numbers. I have the Unofficial Legendary Edition patch installed along with a metric ♥♥♥♥-ton of mods with it, but none affecting the Civil War questline itself. If anyone could come back with info, I'd much appreciate it.

[Adversary]

I had this issue myself, today ironically enough. First and only time I've had it. There is a list of solutions that you can utilize on UESP. Note that this is a catch-all regarding "Reunification of Skyrim", as that was the quest I was having issues with personally.

UESP.net původně napsal:

At various points throughout the questline, Legate Rikke may not give you the next mission or will not acknowledge you "reporting for duty".

The most reliable way to bypass this bug is to go to any indoor location and wait/rest for 30+ days. This allows all location cells to refresh, and the next time you travel to the Winterhold Imperial Camp, Legate Rikke will offer the "Reporting for Duty" dialog option.
One way to fix this is to ask General Tullius "How goes the war?" until the phrase is no longer white (the indicator that he has something new to say). He will give you some information about every battle you've won, initiating the 'Reporting for duty' prompt with Legate Rikke.
Another way to fix the problem is to activate the werewolf form, wait until the end of it, and talk to Rikke again.
PC - Entering this code into the console fixes this glitch and causes the dialogue option to immediately appear: movetoqt CWObj
PC - Using the command "moveto" to move Rikke to another location(inside a city, or an inn, player home, everything but skyrim world), talking to her and then moving her back to imperial camp seems to fix the dialogue.
PC - All problems with Rikke not giving "Reporting for duty" dialogue can be fixed by going to another Imperial Camp and using the console command prid 198BB to target Rikke, then use moveto player and talking to Rikke.
PC - Going outside the camp and killing an enemy also resets Rikke sometimes allowing the normal continuation of the quests without the need for console commands or any other fix
PC - Head to Tullius in solitude. Talk to him, then exit out and open up the console (might not be necessary but that's what I've done). Enter "GetStage cwobj" to verify the variable is set to 1.00. If it is so, enter "ResetQuest CWObj. Use "GetStage" to confirm the quest stage is 0.00. Enter "SetStage CWObj 1." Close the console window and return to Rikke. You should get the "Reporting in" Dialog option.
PC - If nothing else works, you may need complete the entire Reunification of Skyrim quest via the console command setstage cwobj 255. You cannot use the console to start the next quest within the series, as the bug applies to the over-arching quest. - This is not a fix. This simply makes the game think the quest is finished, but Ulfric is still alive, nothing has changed throughout the game.

Last one is the one I did. Hope this helps.

Source: https://en.uesp.net/wiki/Skyrim:Reunification_of_Skyrim