Monks gain the Empty Body feature (PHB, page 79):
Beginning at 18th level, you can use your action to spend 4 ki points to become invisible for 1 minute. During that time, you also have resistance to all damage but force damage.
"During that time" is a bit ambiguous to me. It implies that it's connected to the duration of one minute, but not necessarily to being invisible yet it isn't clear. However, this description doesn't mention any saves or concentration required for staying invisible, after taking damage for example. But since monks are all about controlling their own body and mind, it would make sense to me to become visible at will.
Is it possible to break the invisibility while keeping the resistances?
If so, how?
Being invisible for a minute can be handy, but as the sole frontliner of our party (bard, mystic, sorcerer) it's not always preferable in combat. Often I actually want the enemies to see me, but I wouldn't mind the resistances.
For this question I'm only interested in the RAW.
You become invisible for 1 minute. This is not like the invisibility spell; it is the invisible condition.
There is no concentration. There is no using an action to end it by RAW. Attacking does not end it. And it lasts 1 minute. During that time you have resistance to all damage but force.
It is not possible without DM permission to be visible. However, the enemy can still know where you are based off sound so just make sure the enemies hear you as you attack them. Thus you get resistance and it's hard to hit you.