Just used the add gold function and it's working perfectly fine for me. Make sure you are using the correct trainer (either Uplay Plus version or the Uplay+Steam Version depending on which one you have). Ver. 1.5.3
You should dload to a folder that has been excluded from your security software. It sounds like real-time scanning is still running even tho you disabled the main program. Many of them do that.
[Edited by Jaks, 3/21/2020 9:05:51 PM]