The BLE SENSE has TWO COM ports.
The second COM port also often referred to as “BOOTLOADER” can be invoked by quickly double tapping the reset button.
It can also be used to help clear out a sketch that does not behave. For that put it into BOOTLOADER then upload either BLINK or BARE MINIMUM from the EXAMPLES.
The IDE knows and expects this and can handle it.
Most often there is no need to chase the new COM port.
However there have been some scenarios with other boards of this nature where over aggressive antivirus, Cloud / network or portable based IDE installs can cause delays which result in some problems.
If yours is one of those types of problem then unless you have some decent knowledge of networking etc. it is often best to uninstall the IDE and re-install to a local drive
If you think it is antivirus / security based then you need to add the install locations to your whitelist / exclusions.
Another is USB 3.x issues. There are well known not just for Arduino but other USB peripherals too.
It can be your computers CHIPSET that may not be fully compliant. The most common fix is to insert a USB 2.0 hub between the Arduino (or errant peripheral ). This acts as a buffer in most cases
Last but not least are USB driver issues under Windows. If your USB drivers were supplied by Microsoft you should consider going to the hardware manufacturer site and getting the proper drivers as microsoft has a habit of breaking some of the drivers. This extends beyond USB with the second largest problem being Graphics card drivers supplied by microsoft.
Please rule all those aspects out first.
Also including a pdf that may help with some of those aspects (but not all)
CLEAN UP BEFORE INSTALLING ANOTHER COPY OF THE IDE OR ARDUINO CREATE.pdf (347 KB)