After using Jacdac it is not possible to connect to the app!
The BLE-matrix is available (on V3, on V2 or V1 not), but the app cannot connect to it. Therefore I would suggest to check/change BLE settings for the Jacdac extension. I think this has also been discussed here: https://github.com/microsoft/pxt-microbit/issues/5521
However, I think there is a difference in using it together or using one after another and that has not been the focus in that issue.
After using Jacdac it is not possible to connect to the app! The BLE-matrix is available (on V3, on V2 or V1 not), but the app cannot connect to it. Therefore I would suggest to check/change BLE settings for the Jacdac extension. I think this has also been discussed here: https://github.com/microsoft/pxt-microbit/issues/5521 However, I think there is a difference in using it together or using one after another and that has not been the focus in that issue.