The European Broadcasting Union has confirmed in-ear issues were the reason for second performances for Malta, Romania, and Ukraine.
A statement from the EBU reads:
Due to issues with the in-ear monitoring during the performances of Malta, Romania, and Ukraine at the 2nd Dress Rehearsal for Semi-Final 1 on Monday 17 May, in accordance with the rules, all artists were given the chance to perform their songs again for the national juries voting on the show.
The technical issue is being thoroughly investigated ahead of the live broadcast of Semi-Final 1 on Tuesday 18 May.
You can follow coverage of the jury show live below.
Source: EBU | Image Source: EBU / Thomas Hanses