Potty Training advice needed pls

I have a 22 week old pup, I’ve had her since she was 13 weeks old. Potty training hasn’t been terrible, compared to my last dog she’s catching on slower but only a few accidents here and there. I trained her how to use a bell and so she tells me when she needs to go out. Here’s my problem. She’s so good with the bell, I can sit in the living room or bedroom with her all day and she will have 0 accidents and will go ring the bell. Problem is the MINUTE I start being productive she pees somewhere. I don’t understand this at all. The first couple of times I thought it was because she rung the bell faintly and I didn’t hear it. But I’m still attentive even when busy and she doesn’t do that, doesn’t even go near the door. She just…pees. Today, the straw that broke the camels back, I took her outside, she peed. I brought her back inside she played for about 10 minutes, and then I got up to get ready and she just peed on my bed. No UTI, I’ve had her urine screened by vet in case of that because she’s been doing this every now and then for a few weeks. Is this a behavior thing? Do I have to go back to tethering? She holds her pee for 8 hours at night so I don’t understand why during the day she pees on the floor or in today’s case my BED always less than 2 hours after having peed outside. Any advice would be great, I just don’t know how to get her to not do this.