What exact settings are you using?
The default "Enemy aggressiveness" of 2 shouldn't produce such behavior.
But if you use a higher value or enable "Inherit unit aggression", the AI uses the unit's aggression-setting to enact certain behaviors, which likely are sub-optimal from their perspective.
If the AI is easy to camp on "Enemy aggressiveness" of 2, then it's something I shall take a look at. If it happens on the aforementioned settings, then it's kinda intended for those.
Good day!
This comment may be outdated, because last version of BAI I played with was 7.6.8.
I was frequently switching between aggressiveness 2 and 3. Because it became too boresome watching same tactics BAI uses for every fraction.
May I take little of your time for better understanding of the idea behind my words? Below is basic table of scenarios.
Most battlescape scenarios player prefers to choose lay within white-green section, when player has 100% success probability, while evil modders tend to create battlescape scenarios within magenta-white area. That's sort of plot-moving force, so player feels the tension and overcoming of cruelties. It's also classic RPG scenario: to get something to deal with someone. X-COM is sort of RPG, too. Because, as I have it written many times, player has to raise soldier units from useless autistic battlescape meat into supersoldiers via in-battle experience and geoscape trainings and transformations. The battlescape tension curve is considered by modders.
(Please note that Weapon power and Armor effectiveness are relative to average enemy on battlescape. I mean: RPG should be considered somewhere 3.5 vs power armor, gauss tank barrel is 5.0, while AK-47 should be considered 1 because it will never inflict any harm)
While 1-1 and 5-5 scenarios are generally uncommon, there are multiple missions with all possible variants of balance.
I will try to compare player's and BAI winning strategies for extremes:
1-1: Within this scenario, in most cases player couldn't win if not blind luck (or cheating)
2-2: Weak player units, the only possibility for player to win is in-door camping, or camo, use of flares and other tricks + peeking. In this case BAI should attack immediately, not prefer to hide first. Also, BAI can take open positions for preserved reaction fire, because it has good chances to survive and kill in return.
5-2: Weaker player units with strong weapons. The best solution for player is reaction fire from camo positions. Because BAI ordinarily prefers to hide first, and only then to peek and attack, then go back, losing more than 50% of it's TU on movement. BAI has three scenarios:
- hide and wait till player comes first and reaction-fire his units;
- peek and suppress with explosives and no-LoS fire;
- or zerg-rush the position with possibility of player units miss or get out of reserved TU's
2-5: Player units are terminators with machetes: Player rushes for enemy openly, while BAI can't do much about it. It fires, but no particular harm being inflicted. The only relevant tactics for BAI are best available weapons and explosives. There passing weapons to each other could help (like, passing assault machinegun to other unit wielding pistol), if this is possible.
5-5: Player's forces are OP in all ways: BAI has no chances to win.
While considering extremes is kind of a wrong game overall, the scale of armor/weapon power (multiply) unit amount can be used for getting number of threat points to correct the strategy BAI uses to deal with player's invasion.
Like,
for scenario 2-2 BAI acts with all possible means, suppresses more + reserves a lot of reaction fire at least for half of it's units, while others move forward;
for scenario 4-2 BAI, depending on layout, acts in more hidden manner or rudely exchanges chess pieces on rush (when amount of BAI units is >> amount of player units).
for scenario 2-4 BAI relies more on most powerful weapons and explosives
All this has been written in sole purpose to convince you that there are tons of possible stuff going on and reserving TU's for reaction fire is sometimes good. I don't know on which conditions your BAI taught itself, but in 50% of major mods missions it feels like a brutalless castrate who prefers to hide instead of punch the problem into the face. Who would run away in a power armor vs some black powder guns? Also, almost no reaction fire means less gaming experience and adventure of possibilities (making game more routine and less excited).
UPD. Ofc this is oversimplified model, for many other factors should be considered before strategy review. For discussion.