Hi,
At this point, because i'm not really a expert at these, i would not know how to recommend steps that would be approved by FTB.
However, you can try downloading Java Version 8 Update 221 64bit (build 1.8.0_221-b11)
Then remove the newer version of java and see if it helps
Reason why i ask you to try download the above build is because i am running it and it does not encounter any issue.
IF you prefer not to do it, then just wait for a update released for the launcher at FTB website to see if it will address this issue
Thanks