as far as I can remember, before I gave up migrating to AS6, I realized that the FUBs which might be used as a replacement do not need the LCCounter as a time source. But I might be wrong.
IMHO that’s a topic where B&R should be in charge. They discontinued a whole bunch of libraries without providing a proper guide how to replace them when migrating from a 4.x project.
Agree with Marcus. If you do not get a usable answer here, please contact B&R support. They may provide you with a workaround. Please update us here as well. Marked this reply as a solution but feel free to change it.