after effects warning: roto brush strokes cannot be added until the current frame has finished rende

im kinda new in this thing called rotobrush but i have used this for several times and this problem never showed up. anyway now when im trying to roto it always pop up this alert: after effects warning: roto brush strokes cannot be added until the current frame has finished rendering. even the render after importing the video. what should i do?

btw is it just on my compter or after effects is really slow? i mean like  import 15  sec video in hdr resulution to the timeline the little rendering procces take like 1 minute. about what?? and also the roto itselves its render soooo slow. and i work with new laptop 4060 i7 32 ram i dont get it