With in-game mail that has now gone out to all affected players, we have refunded the cost of skill purchases that were made on Monday, November 9 between 22:17 CET and 23:17 CET when the WoW: Forever servers experienced issues that caused some players to lose training they purchased.
If you were affected by this issue during that timeframe, check your in-game mail for gold equaling the cost of training that you purchased and lost.
Thank you very much for your patience and understanding.