Same thing happened to me. I opened a support ticket and they manually completed the objective for me.
"Thank you for contacting us with this concern. I understand that you have fully explored the Monthly Thronebreaker Event Quest but the Solo Objective has not marked as completed.
I understand that you are concerned about the incomplete Solo Objective and we do have opportunities to assist players with that under specific circumstances. I have reviewed this account, and since it did qualify for support to mark it as completed, I have completed your request.
If you have any other questions or concerns, please do not hesitate to include them in your reply."
Hey guys, I figured out, the reason, This month, I was already a paragon and being a paragon I explored 100% ThroneBreaker Monthly EQ and I got paragon Gaunglet, and I have completed my Paragon Gaunglet difficulty. So the point is, We need to be Paragon before exploring 100% ThroneBreaker Difficulty.
Hey guys, I figured out, the reason, This month, I was already a paragon and being a paragon I explored 100% ThroneBreaker Monthly EQ and I got paragon Gaunglet, and I have completed my Paragon Gaunglet difficulty. So the point is, We need to be Paragon before exploring 100% ThroneBreaker Difficulty.
Comments
Send a ticket and see if support can help
"Thank you for contacting us with this concern. I understand that you have fully explored the Monthly Thronebreaker Event Quest but the Solo Objective has not marked as completed.
I understand that you are concerned about the incomplete Solo Objective and we do have opportunities to assist players with that under specific circumstances. I have reviewed this account, and since it did qualify for support to mark it as completed, I have completed your request.
If you have any other questions or concerns, please do not hesitate to include them in your reply."
So the point is,
We need to be Paragon before exploring 100% ThroneBreaker Difficulty.