Hey All,
I'm having a similar problem using Jetpack (by the same author as Space Exploration). It looks like jetpacks (specifically the armor grid item, not the jump suit) is overriding reach settings upon activation/deactivation.
I was able to temporarily fix this by adding the following event to the list of events that trigger an update.
Within control.lua (Line: 21)
script.on_event({defines.events.on_runtime_mod_setting_changed, defines.events.on_player_joined_game, defines.events.on_player_changed_force, defines.events.on_player_respawned},
to
script.on_event({defines.events.on_runtime_mod_setting_changed, defines.events.on_player_joined_game, defines.events.on_player_changed_force, defines.events.on_player_respawned, defines.events.on_gui_opened},
While this does refresh the settings whenever we open the inventory, it doesn't resolve the underlying issue caused by the other mod. Additionally there is another side effect in which these settings are now force overriding other mods like "Cargo Ships" that adjusts the settings when a 'water rail' is in hand (normally holding water items grants 10x reach distance to allow you to create shipping paths far in the water.
Again this is a hack/bandaid at best, the real solution is to have jetpack simply pass through existing values rather than reset them, but I figured it was worth sharing. The authors of Jetpack were made aware of the issue, so hopefully after an update from them everything will be fine.