5G UE does not report inter-frequency neighboring cell measurements

Hi Experts,

In an Rel.15 SA scenario, I’m trying to configure (RRC Reconfiguration) an UE to report measurements about inter-frequency neighboring cells.

The MeasConfig includes 2 measID related to 2 different MeasObject (1 for the serving cell and the other for the neighbor one). The reportConfig is configured as periodical for both.

The 2 MeasObjects include info for ssbFrequency, ssbSubcarrierSpacing, referenceSignalConfig, quantityConfigIndex and smtc1.

But the UE only sends the periodical report including only the measID configured for the servingCell. No reports are sent for the neighboring.

Looking at the UE Capabilities the relevant measAndMobParameters are supported.
I’m not understanding how the UE shall get the synchro with the inter-frequency neighboring cell to perform the measurement (or to trigger an A-Event for handover).

Can anyone help me to understand?

UE likely needs measurement gap specifically if there is no CA configured

Thanks for your replay O.B.
Including measurements gap the UE sends a report for each measID but it is still not reporting the measurements for the neighboring inter-frequency cell.

From TS 38.133 sec 9.1.3.2a the UE shall monitor 7 NR SSB inter-frequency carriers configured by PCell.
Are these SSB inter-frequency carrier the ones configured by SIB4 in the interFreqCarrierFreqList?