s140 pc-ble-driver 4.0.0 freezes when receiving too many data

I have a nRF52840-PCA10059 dongle.

I have a PCA10040 dev boeard on which I programmed the ble_app_hrs_freertos_pca10040_s132 example after I modified HEART_RATE_MEAS_INTERVAL and BATTERY_LEVEL_MEAS_INTERVAL variables (lines 100 and 95 of main.c) with value 10 (10ms for 100Hz).

If I connect this fast "Nordic_HRM" using nRF Connect (it programmed my dongle with API v3 SoftDevice, I can connect and get notifications from the device.

If I connect this fast "Nordic_HRM" using heart_rate_collector_v3 or heart_rate_collector_v6 example programs (compiled from https://github.com/NordicSemiconductor/pc-ble-driver/tree/v4.0.0), then I only get a few notifications and then the app freezes.

When it's frozen, using a debugger I can see that UartBoost::readHandler is not called anymore. If I press Enter (supposed to toggle notifications OFF), I see written

"Setting HRM CCCD"

I see:

UartBoost::readHandler receives: c0 10 0 0 f0 c0 c0 d6 6e 0 bc 1 9c 11 0 0 0 61 3e c0
SerializationTransport::readHandler receives: 1 9c 11 0 0 0

But "Received write response." never shows up. Looks like the soft device freezed and does not send my anything.

When using heart_rate_collector_v2 with a old nRF51 dongle, I observe no freezing.

When using heart_rate_collector_v3, I kept the SoftDevice programmed by "nRF Connect". Also tried with connectivity_4.0.0_usb_with_s132_3.1.0.hex, same behaviour observed.

When using heart_rate_collector_v6, I used connectivity_4.0.0_usb_with_s140_6.1.0.hex.

"Nordic HRM" unmodified device (low sampling rate) does not freeze.

Any ides what could cause this? What does nRF Connect make differently than heart_rate_collector sample?