Can anyone help me ,

I sent piper to sanctuary but she is not there , and i can not find her anywhere , i have checked all my settlements and all bases , checked diamond city where i found her and she is not there either. is this a known bug? is she gone forever unless i start a new game.

any advice?

I lost her once. I found her at Nick's office.

ok , i will check there

nope she was not there either ......

The same happened to me. I decided to just stay with one follower until it's patched

Hmm, have you placed a bell in Sanctuary to gather all the settlers? When I lost her, someone said he sent her to Sanctuary but couldn't find her until he placed a bell and used it to gather them all and Piper appeared.

yes i have tried the bell , she is MIA , annoying as she has alot of my weapons on her

How far away were you from Sanctuary when you sent her there? Dismissed companions take a super long time to walk to wherever you send them, so if you were way down south it could take her a while. Try doing some other stuff for a few in-game days, then go back to Sanctuary and ring the bell, and keep ringing it until you are pretty sure everyone has responded. One time Preston pretty much ignored my bell, or something... I knew he was there somewhere, but he didn't respond. I think I fixed that by fast traveling away, then back again, then ringing the bell again, and that time he showed up right away. Could be a combo of glitch and sluggish companions with bad pathing (I suspect that probably when Preston didn't respond, he was stuck walking into a wall or something lol).

I've been using her but she tends to get lost. I had to go to my base and sleep overnight before she appeared.

I think she fell off a building we were clearing (she's always testing gravity) and was probably laying on the ground waiting for a stimpak. Course I couldn't find her so I couldn't give her one.

Sometimes she turns upside down through the earth andyou can only see the bottom of her feet, and sometimes she just gets lost and is stuck on some random thing in the world and is impossible to find, never ever send away companions you ever want to use aagain unless you have a map marker for them. Hope someone makes a mod showing all companions on your map.