Bitcoin Core shows the address Electrum says does not belong to my wallet (MPK imported via EPS). what’s the matter?

I’m running a full node (pruned) with Bitcoin Core over Tor. I installed Electrum Personal Server (EPS) and connected my hardware wallet to Electrum via Tor. We created a surveillance-only wallet in Bitcoin Core in a hardware wallet by providing the master public key in the config.ini file (no other master public key, just one of the hardware wallets shown in Electrum). Everything works. The Electrum will display a green circle. This means I am only connected to my node and my wallet is visible to Bitcoin Core.

However, according to Electrum, Bitcoin Core’s “receiving address” shows an address that does not belong to my wallet. I tried sending a test amount to one of Bitcoin Core’s addresses that isn’t visible in Electrum. Now this transaction shows up in Bitcoin Core as belonging to one of my watch-only addresses, but it doesn’t show up in Electrum. Electrum’s ismine(“address”) command returns false. Additionally, you cannot sign messages with an address in Electrum that your hardware wallet is connected to, because Electrum says the address does not belong to the wallet.

After double-checking that there was only one MPK mentioned in EPS’ config.ini file, I created a new wallet in Bitcoin Core and synced EPS again. Same problem: my wallet now shows different amounts in Electrum (without that address) and Bitcoin Core (with the address mentioned above). In addition to this address where I sent the test transaction, Bitcoin Core is showing many other addresses that are not in Electrum.

How is this possible? Bitcoin core wallet has private keys disabled, empty wallet, name “electrumpersonalserver” so it should be EPS only and it only imports and masters public keys so shouldn’t it contain only addresses derived from one master public key?

Is the problem that Bitcoin Core derived addresses from a master public key that Electrum has not yet generated? But I think Electrum should recognize all addresses that belong to the wallet (and I can’t sign a message with an address in my Electrum wallet because ismine returned false and says the address doesn’t belong to the wallet). Or should I import the master public key via the EPS config.ini file (and rather via the Bitcoin Core console)?

I would be very grateful for any help and insight into what is going on here. Thank you in advance!