No new UpdateTip. Just "Pre-allocating up to position ..."
If you're seeing pre-alloc messages but no UpdateTip messages, it means that you're receiving blocks from peers, but not the next block you need.
Bitcoin Core tries to spread downloading of blocks among multiple peers. However, once a block has been requested, it won't get requested again as long as that request is still outstanding with the peer it's already requested from - until that peer goes offline, or the request times out (at which point the peer is disconnected too).
However, validation requires consecutive blocks, eventually. If we've processed all blocks until number N, we need block number N+1 to continue. It's possible that the request for block N+1 was sent to a non-responsive peer, while other blocks (N+2, N+3, ...) are requested from other peers who are responding. Validation won't proceed until N+1 is received. There are some heuristics to detect such straggling peers and disconnect them (you'd see &quot;Peer X is stalling block download&quot; messages when this happens, I believe), but it's not perfect.